Systems and methods for application specific load balancing

ABSTRACT

The present application is directed towards systems and methods for application specific load-balancing for web servers. A device intermediary to a plurality of clients and a plurality of services executing on a plurality of servers, may receive a request from a client for an application. The device may identify an identifier for the application from a table comprising a list of applications and a corresponding identifier assigned to each application. In an embodiment, the device may establish one or more monitors to monitor each service to determine applications available on each service. In an embodiment, the device may determine that one or more services of the plurality of services provides the application and select a service from the one or more services to forward the request. The device may forward the request to the selected service.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the file or records of thePatent and Trademark Office, but otherwise reserves all copyright rightswhatsoever.

FIELD

The present application generally relates to data communicationnetworks. In particular, the present application relates to systems andmethods for application specific load balancing.

BACKGROUND

Load balancing is a method for distributing workloads across multiplecomputing resources and these resources typically have the samecharacteristics. For example, in application load balancing amongservers, servers typically have the same set of applications and arehomogenous in terms of application availability. In performing loadbalancing among one or more servers executing a plurality of services,any differences in the types of applications available on the one ormore servers can cause challenges.

BRIEF SUMMARY

The present application is directed towards systems and methods forapplication specific load balancing among servers. The systems andmethods described herein allow for servers to be load balanced despitedifferences in terms of application and application availability. Thesystems and methods load balance client requests for applications basedon application availability on one or more servers. In one aspect, themethod includes receiving, by a device intermediary to a plurality ofclients and a plurality of services executing on a plurality of servers,a request from a client for an application. The device may identify anidentifier for the application from a table comprising a list ofapplications and a corresponding identifier assigned to eachapplication. The method further includes determining, by the deviceusing the identifier, that one or more services of the plurality ofservices provide the application and selecting a service from the one ormore services to forward the request. The method further includesforwarding, by the device, the request to the selected service.

In some embodiments, the method includes establishing, by the device,one or more monitors to monitor each service to identify applicationsavailable on each service. The device may maintain, responsive tomonitoring by the one or more monitors, the list of applications in thetable available for each service. In an embodiment, the method mayinclude querying, by the device using the identifier, a second tablecomprising a list of identifiers available for each service. The devicemay determine that the one or more services are identified in the secondtable with the identifier corresponding to the application. In someembodiments, the method includes selecting, by the device, the servicethat is determined to be available. The method may further includedetermining, by the device, that a monitor is enabled for the serviceand the service has the application.

In another aspect, the method may include establishing, by a deviceintermediary to a plurality of clients and a plurality of servicesexecuting on a plurality of servers, one or more monitors to monitoreach service to determine applications available on each service. Thedevice may determine a number of applications available on each serviceand assign an identifier to each application available via the pluralityof services. The method further includes maintaining, by the deviceresponsive to monitoring, a table comprising identification of eachservice of the plurality of services and a list of identifierscorresponding to each application available via each service.

In some embodiments, the method includes receiving, by the device,responses from probes of the one or more responses. The monitorresponses may indicate applications available on the respective service.In an embodiment, the device may establish a second table comprising alist of applications and corresponding identifiers assigned to eachapplication in the list of applications. In some embodiments, the devicemay compare responsive to monitoring, the list of identifiers availablefor each service in the table and update the table responsive to thecomparison. In an embodiment, the device may receive a request from aclient for an application. The device may identify the identifier forthe application and determining using the identifier via the table, thatone or more services of the plurality of services provide theapplication. In some embodiments, the device may select a service fromthe one or more services to forward the request and forwarding, by thedevice, the request to the selected service.

In another aspect, the present disclosure is directed towards a systemfor application specific load balancing. The system includes a deviceintermediary to a plurality of client and a plurality of servicesexecuting on a plurality of servers. In an embodiment, the device can beconfigured to receive a request from a client for an application andidentify an identifier for the application from a table comprising alist of applications and a corresponding identifier assigned to eachapplication. The device can further be configured to determine, usingthe identifier, that one or more services of the plurality of servicesprovides the application and select a service from the one or moreservices to forward the request. The device may be configured to forwardthe request to the selected service.

In some embodiments, the device can be configured to establish one ormore monitors to monitor each service to identify applications availableon each service. The device may be configured to maintain, responsive tomonitoring by the one or more monitors, the list of applications in thetable available for each service. In an embodiment, the device can befurther configured to query using the identifier, a second tablecomprising a list of identifiers available for each service. The devicemay be configured to determine that the one or more services areidentified in the second table with the identifier corresponding to theapplication. In some embodiments, the device may be configured to selectthe service that is determined to be available.

The details of various embodiments of the invention are set forth in theaccompanying drawings and the description below.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment fora client to access a server via an appliance.

FIG. 1B is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anappliance.

FIG. 1C is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance.

FIG. 1D is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance.

FIGS. 1E-1H are block diagrams of embodiments of a computing device.

FIG. 2A is a block diagram of an embodiment of an appliance forprocessing communications between a client and a server.

FIG. 2B is a block diagram of another embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server.

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance.

FIG. 4A is a block diagram of an embodiment of a virtualizationenvironment.

FIG. 4B is a block diagram of another embodiment of a virtualizationenvironment.

FIG. 4C is a block diagram of an embodiment of a virtualized appliance.

FIG. 5A are block diagrams of embodiments of approaches to implementingparallelism in a multi-core system.

FIG. 5B is a block diagram of an embodiment of a system utilizing amulti-core system.

FIG. 5C is a block diagram of another embodiment of an aspect of amulti-core system.

FIG. 6 is a block diagram of an embodiment of a cluster system.

FIG. 7A is a block diagram of an appliance for using a plurality ofmonitoring agents to monitor network services.

FIG. 7B is a block diagram of an embodiment of a table on a core usedfor monitoring in a multi-core system.

FIG. 7C is a flow diagram of an embodiment of a method for configuring atable used for monitoring in a multi-core system.

FIG. 7D is a flow diagram of an embodiment of a method for monitoringservices in a multi-core system.

FIG. 7E is a flow diagram of an embodiment of a method for updating thestate of a service according to the results of monitoring the servicesin a multi-core system.

FIG. 8A is a block diagram of an embodiment of a system for monitoringin a cluster.

FIG. 8B is a flow diagram of an embodiment of a method for distributedmonitoring of one or more services across a plurality of nodes in acluster system.

FIG. 8C is an illustrative diagram of a method for monitoring in acluster system.

FIG. 8D is a flow diagram of a configuration event in a cluster system.

FIG. 8E is a flow diagram of another configuration change in a clustersystem.

FIG. 8F is a flow diagram illustrating when a node leaves a cluster.

FIG. 8G is a flow diagram for a method for redistribution of ownershipof services in a cluster system.

FIG. 9A is a block diagram of an appliance used for monitoring of one ormore services across a plurality of nodes in a cluster system using pathmonitoring.

FIG. 9B is a diagram of a method for monitoring of one or more servicesacross a plurality of nodes in a cluster system.

FIG. 9C is one illustrative example of a method for monitoring servicesin a cluster using path monitors.

FIG. 9D is a diagram of a method for handling dynamic response timemonitors.

FIG. 10A is a block diagram of a system application specific loadbalancing for web servers.

FIG. 10B is a block diagram of an embodiment of a table used forload-balancing among web servers.

FIG. 11A is a diagram of a method for application specific loadbalancing for web servers.

FIG. 11B is a diagram of a method for monitoring servers to load-balancethe servers.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION

For purposes of reading the description of the various embodimentsbelow, the following descriptions of the sections of the specificationand their respective contents may be helpful:

Section A describes a network environment and computing environmentwhich may be useful for practicing embodiments described herein.

Section B describes embodiments of systems and methods for delivering acomputing environment to a remote user.

Section C describes embodiments of systems and methods for acceleratingcommunications between a client and a server.

Section D describes embodiments of systems and methods for virtualizingan application delivery controller.

Section E describes embodiments of systems and methods for providing amulti-core architecture and environment.

Section F describes embodiments of systems and methods for providing aclustered appliance architecture environment.

Section G describes embodiments of systems and methods for monitoring ina multi-core system.

Section H describes embodiments of systems and methods for monitoring ina cluster system.

Section I describes embodiments of systems and methods for applicationspecific load-balancing.

A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environmentcomprises one or more clients 102 a-102 n (also generally referred to aslocal machine(s) 102, or client(s) 102) in communication with one ormore servers 106 a-106 n (also generally referred to as server(s) 106,or remote machine(s) 106) via one or more networks 104, 104′ (generallyreferred to as network 104). In some embodiments, a client 102communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, a plurality of appliances 200 may be deployedon network 104′. In one embodiment, a first appliance 200 communicateswith a second appliance 200′. In other embodiments, the appliance 200could be a part of any client 102 or server 106 on the same or differentnetwork 104,104′ as the client 102. One or more appliances 200 may belocated at any point in the network or network communications pathbetween a client 102 and a server 106.

In some embodiments, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale Fla.,referred to as Citrix NetScaler devices. In other embodiments, theappliance 200 includes any of the product embodiments referred to asWebAccelerator and BigIP manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 205 includes any of the DXacceleration device platforms and/or the SSL VPN series of devices, suchas SA 700, SA 2000, SA 4000, and SA 6000 devices manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In yet another embodiment, theappliance 200 includes any application acceleration and/or securityrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco ACE Application Control EngineModule service software and network modules, and Cisco AVS SeriesApplication Velocity System.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, an embodiment of a network environmentdeploying multiple appliances 200 is depicted. A first appliance 200 maybe deployed on a first network 104 and a second appliance 200′ on asecond network 104′. For example a corporate enterprise may deploy afirst appliance 200 at a branch office and a second appliance 200′ at adata center. In another embodiment, the first appliance 200 and secondappliance 200′ are deployed on the same network 104 or network 104. Forexample, a first appliance 200 may be deployed for a first server farm38, and a second appliance 200 may be deployed for a second server farm38′. In another example, a first appliance 200 may be deployed at afirst branch office while the second appliance 200′ is deployed at asecond branch office′. In some embodiments, the first appliance 200 andsecond appliance 200′ work in cooperation or in conjunction with eachother to accelerate network traffic or the delivery of application anddata between a client and a server.

Referring now to FIG. 1C, another embodiment of a network environmentdeploying the appliance 200 with one or more other types of appliances,such as between one or more WAN optimization appliance 205, 205′ isdepicted. For example a first WAN optimization appliance 205 is shownbetween networks 104 and 104′ and a second WAN optimization appliance205′ may be deployed between the appliance 200 and one or more servers106. By way of example, a corporate enterprise may deploy a first WANoptimization appliance 205 at a branch office and a second WANoptimization appliance 205′ at a data center. In some embodiments, theappliance 205 may be located on network 104′. In other embodiments, theappliance 205′ may be located on network 104. In some embodiments, theappliance 205′ may be located on network 104′ or network 104″. In oneembodiment, the appliance 205 and 205′ are on the same network. Inanother embodiment, the appliance 205 and 205′ are on differentnetworks. In another example, a first WAN optimization appliance 205 maybe deployed for a first server farm 38 and a second WAN optimizationappliance 205′ for a second server farm 38.′

In one embodiment, the appliance 205 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic, such as traffic toand/or from a WAN connection. In some embodiments, the appliance 205 isa performance enhancing proxy. In other embodiments, the appliance 205is any type and form of WAN optimization or acceleration device,sometimes also referred to as a WAN optimization controller. In oneembodiment, the appliance 205 is any of the product embodiments referredto as Lansdale manufactured by Citrix Systems, Inc. of Ft. Lauderdale,Fla. In other embodiments, the appliance 205 includes any of the productembodiments referred to as BIG-IP link controller and WAN jetmanufactured by F5 Networks, Inc. of Seattle, Wash. In anotherembodiment, the appliance 205 includes any of the WAX and WACO WANacceleration device platforms manufactured by Juniper Networks, Inc. ofSunnyvale, Calif. In some embodiments, the appliance 205 includes any ofthe steelhead line of WAN optimization appliances manufactured byRiverbed Technology of San Francisco, Calif. In other embodiments, theappliance 205 includes any of the WAN related devices manufactured byExpand Networks Inc. of Roseland, N.J. In one embodiment, the appliance205 includes any of the WAN related appliances manufactured by PicketerInc. of Cupertino, Calif., such as the Packet Shaper, shared, and Skyproduct embodiments provided by Picketer. In yet another embodiment, theappliance 205 includes any WAN related appliances and/or softwaremanufactured by Cisco Systems, Inc. of San Jose, Calif., such as theCisco Wide Area Network Application Services software and networkmodules, and Wide Area Network engine appliances.

In one embodiment, the appliance 205 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 205 includes optimization of Wide Area FileServices (WAFTS). In another embodiment, the appliance 205 acceleratesthe delivery of files, such as via the Common Internet File System(COIFS) protocol. In other embodiments, the appliance 205 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 205 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 205 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 205 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol.

In another embodiment, the appliance 205 encoded any type and form ofdata or information into custom or standard TCP and/or IP header fieldsor option fields of network packet to announce presence, functionalityor capability to another appliance 205′. In another embodiment, anappliance 205′ may communicate with another appliance 205′ using dataencoded in both TCP and/or IP header fields or options. For example, theappliance may use TCP option(s) or IP header fields or options tocommunicate one or more parameters to be used by the appliances 205,205′ in performing functionality, such as WAN acceleration, or forworking in conjunction with each other.

In some embodiments, the appliance 200 preserves any of the informationencoded in TCP and/or IP header and/or option fields communicatedbetween appliances 205 and 205′. For example, the appliance 200 mayterminate a transport layer connection traversing the appliance 200,such as a transport layer connection from between a client and a servertraversing appliances 205 and 205′. In one embodiment, the appliance 200identifies and preserves any encoded information in a transport layerpacket transmitted by a first appliance 205 via a first transport layerconnection and communicates a transport layer packet with the encodedinformation to a second appliance 205′ via a second transport layerconnection.

Referring now to FIG. 1D, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 10 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiments the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

Still referring to FIG. 1D, an embodiment of the network environment mayinclude a monitoring server 106A. The monitoring server 106A may includeany type and form performance monitoring service 198. The performancemonitoring service 198 may include monitoring, measurement and/ormanagement software and/or hardware, including data collection,aggregation, analysis, management and reporting. In one embodiment, theperformance monitoring service 198 includes one or more monitoringagents 197. The monitoring agent 197 includes any software, hardware orcombination thereof for performing monitoring, measurement and datacollection activities on a device, such as a client 102, server 106 oran appliance 200, 205. In some embodiments, the monitoring agent 197includes any type and form of script, such as Visual Basic script, orJavascript. In one embodiment, the monitoring agent 197 executestransparently to any application and/or user of the device. In someembodiments, the monitoring agent 197 is installed and operatedunobtrusively to the application or client. In yet another embodiment,the monitoring agent 197 is installed and operated without anyinstrumentation for the application or device.

In some embodiments, the monitoring agent 197 monitors, measures andcollects data on a predetermined frequency. In other embodiments, themonitoring agent 197 monitors, measures and collects data based upondetection of any type and form of event. For example, the monitoringagent 197 may collect data upon detection of a request for a web page orreceipt of an HTTP response. In another example, the monitoring agent197 may collect data upon detection of any user input events, such as amouse click. The monitoring agent 197 may report or provide anymonitored, measured or collected data to the monitoring service 198. Inone embodiment, the monitoring agent 197 transmits information to themonitoring service 198 according to a schedule or a predeterminedfrequency. In another embodiment, the monitoring agent 197 transmitsinformation to the monitoring service 198 upon detection of an event.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of any networkresource or network infrastructure element, such as a client, server,server farm, appliance 200, appliance 205, or network connection. In oneembodiment, the monitoring service 198 and/or monitoring agent 197performs monitoring and performance measurement of any transport layerconnection, such as a TCP or UDP connection. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresnetwork latency. In yet one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures bandwidth utilization.

In other embodiments, the monitoring service 198 and/or monitoring agent197 monitors and measures end-user response times. In some embodiments,the monitoring service 198 performs monitoring and performancemeasurement of an application. In another embodiment, the monitoringservice 198 and/or monitoring agent 197 performs monitoring andperformance measurement of any session or connection to the application.In one embodiment, the monitoring service 198 and/or monitoring agent197 monitors and measures performance of a browser. In anotherembodiment, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of HTTP based transactions. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of a Voice over IP (VoIP) applicationor session. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of a remotedisplay protocol application, such as an ICA client or RDP client. Inyet another embodiment, the monitoring service 198 and/or monitoringagent 197 monitors and measures performance of any type and form ofstreaming media. In still a further embodiment, the monitoring service198 and/or monitoring agent 197 monitors and measures performance of ahosted application or a Software-As-A-Service (SaaS) delivery model.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of one or moretransactions, requests or responses related to application. In otherembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures any portion of an application layer stack, such asany .NET or J2EE calls. In one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures database or SQLtransactions. In yet another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures any method, functionor application programming interface (API) call.

In one embodiment, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of a delivery ofapplication and/or data from a server to a client via one or moreappliances, such as appliance 200 and/or appliance 205. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of delivery of a virtualizedapplication. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of delivery of astreaming application. In another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures performance ofdelivery of a desktop application to a client and/or the execution ofthe desktop application on the client. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresperformance of a client/server application.

In one embodiment, the monitoring service 198 and/or monitoring agent197 is designed and constructed to provide application performancemanagement for the application delivery system 190. For example, themonitoring service 198 and/or monitoring agent 197 may monitor, measureand manage the performance of the delivery of applications via theCitrix Presentation Server. In this example, the monitoring service 198and/or monitoring agent 197 monitors individual ICA sessions. Themonitoring service 198 and/or monitoring agent 197 may measure the totaland per session system resource usage, as well as application andnetworking performance. The monitoring service 198 and/or monitoringagent 197 may identify the active servers for a given user and/or usersession. In some embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors back-end connections between theapplication delivery system 190 and an application and/or databaseserver. The monitoring service 198 and/or monitoring agent 197 maymeasure network latency, delay and volume per user-session or ICAsession.

In some embodiments, the monitoring service 198 and/or monitoring agent197 measures and monitors memory usage for the application deliverysystem 190, such as total memory usage, per user session and/or perprocess. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors CPU usage the applicationdelivery system 190, such as total CPU usage, per user session and/orper process. In another embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors the time required to log-into an application, a server, or the application delivery system, such asCitrix Presentation Server. In one embodiment, the monitoring service198 and/or monitoring agent 197 measures and monitors the duration auser is logged into an application, a server, or the applicationdelivery system 190. In some embodiments, the monitoring service 198and/or monitoring agent 197 measures and monitors active and inactivesession counts for an application, server or application delivery systemsession. In yet another embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors user session latency.

In yet further embodiments, the monitoring service 198 and/or monitoringagent 197 measures and monitors measures and monitors any type and formof server metrics. In one embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors metrics related to systemmemory, CPU usage, and disk storage. In another embodiment, themonitoring service 198 and/or monitoring agent 197 measures and monitorsmetrics related to page faults, such as page faults per second. In otherembodiments, the monitoring service 198 and/or monitoring agent 197measures and monitors round-trip time metrics. In yet anotherembodiment, the monitoring service 198 and/or monitoring agent 197measures and monitors metrics related to application crashes, errorsand/or hangs.

In some embodiments, the monitoring service 198 and monitoring agent 198includes any of the product embodiments referred to as EdgeSightmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. In anotherembodiment, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the product embodiments referred to asthe TrueView product suite manufactured by the Symphoniq Corporation ofPalo Alto, Calif. In one embodiment, the performance monitoring service198 and/or monitoring agent 198 includes any portion of the productembodiments referred to as the TeaLeaf CX product suite manufactured bythe TeaLeaf Technology Inc. of San Francisco, Calif. In otherembodiments, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the business service managementproducts, such as the BMC Performance Manager and Patrol products,manufactured by BMC Software, Inc. of Houston, Tex.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Eand 1F depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1E and 1F, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1E, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1E, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1F depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1F the main memory 122 maybe DRDRAM.

FIG. 1F depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1F, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1F depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130 bvia HyperTransport, Rapid I/O, or InfiniBand. FIG. 1F also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 b using a localinterconnect bus while communicating with I/O device 130 a directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein.

A wide variety of I/O devices 130 a-130 n may be present in thecomputing device 100. Input devices include keyboards, mice, trackpads,trackballs, microphones, and drawing tablets. Output devices includevideo displays, speakers, inkjet printers, laser printers, anddye-sublimation printers. The I/O devices 130 may be controlled by anI/O controller 123 as shown in FIG. 1E. The I/O controller may controlone or more I/O devices such as a keyboard 126 and a pointing device127, e.g., a mouse or optical pen. Furthermore, an I/O device may alsoprovide storage 128 and/or an installation medium 116 for the computingdevice 100. In still other embodiments, the computing device 100 mayprovide USB connections to receive handheld USB storage devices such asthe USB Flash Drive line of devices manufactured by Twintech Industry,Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1E and 1F typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufacturedby International Business Machines of Armonk, N.Y.; and Linux, afreely-available operating system distributed by Caldera Corp. of SaltLake City, Utah, or any type and/or form of a Unix operating system,among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

As shown in FIG. 1G, the computing device 100 may comprise multipleprocessors and may provide functionality for simultaneous execution ofinstructions or for simultaneous execution of one instruction on morethan one piece of data. In some embodiments, the computing device 100may comprise a parallel processor with one or more cores. In one ofthese embodiments, the computing device 100 is a shared memory paralleldevice, with multiple processors and/or multiple processor cores,accessing all available memory as a single global address space. Inanother of these embodiments, the computing device 100 is a distributedmemory parallel device with multiple processors each accessing localmemory only. In still another of these embodiments, the computing device100 has both some memory which is shared and some memory which can onlybe accessed by particular processors or subsets of processors. In stilleven another of these embodiments, the computing device 100, such as amulti-core microprocessor, combines two or more independent processorsinto a single package, often a single integrated circuit (IC). In yetanother of these embodiments, the computing device 100 includes a chiphaving a CELL BROADBAND ENGINE architecture and including a Powerprocessor element and a plurality of synergistic processing elements,the Power processor element and the plurality of synergistic processingelements linked together by an internal high speed bus, which may bereferred to as an element interconnect bus.

In some embodiments, the processors provide functionality for executionof a single instruction simultaneously on multiple pieces of data(SIMD). In other embodiments, the processors provide functionality forexecution of multiple instructions simultaneously on multiple pieces ofdata (MIMD). In still other embodiments, the processor may use anycombination of SIMD and MIMD cores in a single device.

In some embodiments, the computing device 100 may comprise a graphicsprocessing unit. In one of these embodiments, depicted in FIG. 1H, thecomputing device 100 includes at least one central processing unit 101and at least one graphics processing unit. In another of theseembodiments, the computing device 100 includes at least one parallelprocessing unit and at least one graphics processing unit. In stillanother of these embodiments, the computing device 100 includes aplurality of processing units of any type, one of the plurality ofprocessing units comprising a graphics processing unit.

In some embodiments, a first computing device 100 a executes anapplication on behalf of a user of a client computing device 100 b. Inother embodiments, a computing device 100 a executes a virtual machine,which provides an execution session within which applications execute onbehalf of a user or a client computing devices 100 b. In one of theseembodiments, the execution session is a hosted desktop session. Inanother of these embodiments, the computing device 100 executes aterminal services session. The terminal services session may provide ahosted desktop environment. In still another of these embodiments, theexecution session provides access to a computing environment, which maycomprise one or more of: an application, a plurality of applications, adesktop application, and a desktop session in which one or moreapplications may execute.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1E and 1F. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may have executableinstructions for performing processing of any security related protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1E and 1F. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although theinvention is not so limited. As such, the appliance 200 can be runningany operating system such as any of the versions of the Microsoft®Windows operating systems, the different releases of the Unix and Linuxoperating systems, any version of the Mac OS® for Macintosh computers,any embedded operating system, any network operating system, anyreal-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices or network devices, or any other operating system capable ofrunning on the appliance 200 and performing the operations describedherein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232, sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 108, and a secondnetwork 110. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example 267 and 267′, and the first transport layerconnection may be established or terminated at one network stack 267,and the second transport layer connection on the second network stack267′. For example, one network stack may be for receiving andtransmitting network packet on a first network, and another networkstack for receiving and transmitting network packets on a secondnetwork. In one embodiment, the network stack 267 comprises a buffer 243for queuing one or more network packets for transmission by theappliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232,a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element may comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comprise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identify, specify, define or configure a caching policy.Policy engine 236, in some embodiments, also has access to memory tosupport data structures such as lookup tables or hash tables to enableuser-selected caching policy decisions. In other embodiments, the policyengine 236 may comprise any logic, rules, functions or operations todetermine and provide access, control and management of objects, data orcontent being cached by the appliance 200 in addition to access, controland management of security, network traffic, network access, compressionor any other function or operation performed by the appliance 200.Further examples of specific caching policies are further describedherein.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for appliance200 to appliance 200 communications. In another embodiment, themulti-protocol compression engine 238 compresses any payload of or anycommunication using a modified transport control protocol, such asTransaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK),TCP with large windows (TCP-LW), a congestion prediction protocol suchas the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, S A P and Siebel, andeven mobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine 238 by executing in the kernel mode204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packet. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200. The GUI 210 or CLI 212 can comprise code running in userspace 202 or kernel space 204. The GUI 210 may be any type and form ofgraphical user interface and may be presented via text, graphical orotherwise, by any type of program or application, such as a browser. TheCLI 212 may be any type and form of command line or text-basedinterface, such as a command line provided by the operating system. Forexample, the CLI 212 may comprise a shell, which is a tool to enableusers to interact with the operating system. In some embodiments, theCLI 212 may be provided via a bash, csh, tcsh, or ksh type shell. Theshell services 214 comprises the programs, services, tasks, processes orexecutable instructions to support interaction with the appliance 200 oroperating system by a user via the GUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202, while in other embodiments, one or more daemon services 218 run inthe kernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. Each of the servers 106 may provide one or more network relatedservices 270 a-270 n (referred to as services 270). For example, aserver 106 may provide an http service 270. The appliance 200 comprisesone or more virtual servers or virtual internet protocol servers,referred to as a vServer, VIP server, or just VIP 275 a-275 n (alsoreferred herein as vServer 275). The vServer 275 receives, intercepts orotherwise processes communications between a client 102 and a server 106in accordance with the configuration and operations of the appliance200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 275 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating to the appliance 200, client 102 orvServer 275. For example, the service 275 may comprise a web server,http server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with avServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine have conditions upon which the policy isapplied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 102 In one embodiment, the appliance 200 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftransport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor IntranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetIP address 282, which is a network identifier, such as IPaddress and/or host name, for the client 102 on the second network 104′.The appliance 200 listens for and receives on the second or privatenetwork 104′ for any communications directed towards the client 102using the client's established IntranetIP 282. In one embodiment, theappliance 200 acts as or on behalf of the client 102 on the secondprivate network 104. For example, in another embodiment, a vServer 275listens for and responds to communications to the IntranetIP 282 of theclient 102. In some embodiments, if a computing device 100 on the secondnetwork 104′ transmits a request, the appliance 200 processes therequest as if it were the client 102. For example, the appliance 200 mayrespond to a ping to the client's IntranetIP 282. In another example,the appliance may establish a connection, such as a TCP or UDPconnection, with computing device 100 on the second network 104requesting a connection with the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of thefollowing acceleration techniques 288 to communications between theclient 102 and server 106: 1) compression; 2) decompression; 3)Transmission Control Protocol pooling; 4) Transmission Control Protocolmultiplexing; 5) Transmission Control Protocol buffering; and 6)caching.

In one embodiment, the appliance 200 relieves servers 106 of much of theprocessing load caused by repeatedly opening and closing transportlayers connections to clients 102 by opening one or more transport layerconnections with each server 106 and maintaining these connections toallow repeated data accesses by clients via the Internet. This techniqueis referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement numbers expected bythe client 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts a DNS requesttransmitted by the client 102. In one embodiment, the appliance 200responds to a client's DNS request with an IP address of or hosted bythe appliance 200. In this embodiment, the client 102 transmits networkcommunication for the domain name to the appliance 200. In anotherembodiment, the appliance 200 responds to a client's DNS request with anIP address of or hosted by a second appliance 200′. In some embodiments,the appliance 200 responds to a client's DNS request with an IP addressof a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Still referring to FIG. 2B, the appliance 200 may include a performancemonitoring agent 197 as discussed above in conjunction with FIG. 2B. Inone embodiment, the appliance 200 receives the monitoring agent 197 fromthe monitoring service 198 or monitoring server 106 as depicted in FIG.2B. In some embodiments, the appliance 200 stores the monitoring agent197 in storage, such as disk, for delivery to any client or server incommunication with the appliance 200. For example, in one embodiment,the appliance 200 transmits the monitoring agent 197 to a client uponreceiving a request to establish a transport layer connection. In otherembodiments, the appliance 200 transmits the monitoring agent 197 uponestablishing the transport layer connection with the client 102. Inanother embodiment, the appliance 200 transmits the monitoring agent 197to the client upon intercepting or detecting a request for a web page.In yet another embodiment, the appliance 200 transmits the monitoringagent 197 to a client or a server in response to a request from themonitoring server 198. In one embodiment, the appliance 200 transmitsthe monitoring agent 197 to a second appliance 200′ or appliance 205.

In other embodiments, the appliance 200 executes the monitoring agent197. In one embodiment, the monitoring agent 197 measures and monitorsthe performance of any application, program, process, service, task orthread executing on the appliance 200. For example, the monitoring agent197 may monitor and measure performance and operation of vServers275A-275N. In another embodiment, the monitoring agent 197 measures andmonitors the performance of any transport layer connections of theappliance 200. In some embodiments, the monitoring agent 197 measuresand monitors the performance of any user sessions traversing theappliance 200. In one embodiment, the monitoring agent 197 measures andmonitors the performance of any virtual private network connectionsand/or sessions traversing the appliance 200, such an SSL VPN session.In still further embodiments, the monitoring agent 197 measures andmonitors the memory, CPU and disk usage and performance of the appliance200. In yet another embodiment, the monitoring agent 197 measures andmonitors the performance of any acceleration technique 288 performed bythe appliance 200, such as SSL offloading, connection pooling andmultiplexing, caching, and compression. In some embodiments, themonitoring agent 197 measures and monitors the performance of any loadbalancing and/or content switching 284 performed by the appliance 200.In other embodiments, the monitoring agent 197 measures and monitors theperformance of application firewall 290 protection and processingperformed by the appliance 200.

C Client Agent

Referring now to FIG. 3, an embodiment of the client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereof.The client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 302 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 203, kernel-mode, 202, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 203and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercept a network communication at any point in the network stack 310,and redirects or transmits the network communication to a destinationdesired, managed or controlled by the interceptor 350 or client agent120. For example, the interceptor 350 may intercept a networkcommunication of a network stack 310 of a first network and transmit thenetwork communication to the appliance 200 for transmission on a secondnetwork 104. In some embodiments, the interceptor 350 comprises any typeinterceptor 350 comprises a driver, such as a network driver constructedand designed to interface and work with the network stack 310. In someembodiments, the client agent 120 and/or interceptor 350 operates at oneor more layers of the network stack 310, such as at the transport layer.In one embodiment, the interceptor 350 comprises a filter driver,hooking mechanism, or any form and type of suitable network driverinterface that interfaces to the transport layer of the network stack,such as via the transport driver interface (TDI). In some embodiments,the interceptor 350 interfaces to a first protocol layer, such as thetransport layer and another protocol layer, such as any layer above thetransport protocol layer, for example, an application protocol layer. Inone embodiment, the interceptor 350 may comprise a driver complying withthe Network Driver Interface Specification (NDIS), or a NDIS driver. Inanother embodiment, the interceptor 350 may comprise a mini-filter or amini-port driver. In one embodiment, the interceptor 350, or portionthereof, operates in kernel-mode 202. In another embodiment, theinterceptor 350, or portion thereof, operates in user-mode 203. In someembodiments, a portion of the interceptor 350 operates in kernel-mode202 while another portion of the interceptor 350 operates in user-mode203. In other embodiments, the client agent 120 operates in user-mode203 but interfaces via the interceptor 350 to a kernel-mode driver,process, service, task or portion of the operating system, such as toobtain a kernel-level data structure 225. In further embodiments, theinterceptor 350 is a user-mode application or program, such asapplication.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, a collection agent 304, and/or monitoring agent 197. In oneembodiment, the client agent 120 comprises an Independent ComputingArchitecture (ICA) client, or any portion thereof, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla., and is also referred to as anICA client. In some embodiments, the client 120 comprises an applicationstreaming client 306 for streaming an application from a server 106 to aclient 102. In some embodiments, the client agent 120 comprises anacceleration program 302 for accelerating communications between client102 and server 106. In another embodiment, the client agent 120 includesa collection agent 304 for performing end-point detection/scanning andcollecting end-point information for the appliance 200 and/or server106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager. Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as a payload of anetwork packet of the transport layer protocol.

The streaming client 306 comprises an application, program, process,service, task or executable instructions for receiving and executing astreamed application from a server 106. A server 106 may stream one ormore application data files to the streaming client 306 for playing,executing or otherwise causing to be executed the application on theclient 102. In some embodiments, the server 106 transmits a set ofcompressed or packaged application data files to the streaming client306. In some embodiments, the plurality of application files arecompressed and stored on a file server within an archive file such as aCAB, ZIP, SIT, TAR, JAR or other archive. In one embodiment, the server106 decompresses, unpackages or unarchives the application files andtransmits the files to the client 102. In another embodiment, the client102 decompresses, unpackages or unarchives the application files. Thestreaming client 306 dynamically installs the application, or portionthereof, and executes the application. In one embodiment, the streamingclient 306 may be an executable program. In some embodiments, thestreaming client 306 may be able to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system and/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments, the client agent 120 includes a monitoring agent197 as discussed in conjunction with FIGS. 1D and 2B. The monitoringagent 197 may be any type and form of script, such as Visual Basic orJava script. In one embodiment, the monitoring agent 197 monitors andmeasures performance of any portion of the client agent 120. Forexample, in some embodiments, the monitoring agent 197 monitors andmeasures performance of the acceleration program 302. In anotherembodiment, the monitoring agent 197 monitors and measures performanceof the streaming client 306. In other embodiments, the monitoring agent197 monitors and measures performance of the collection agent 304. Instill another embodiment, the monitoring agent 197 monitors and measuresperformance of the interceptor 350. In some embodiments, the monitoringagent 197 monitors and measures any resource of the client 102, such asmemory, CPU and disk.

The monitoring agent 197 may monitor and measure performance of anyapplication of the client. In one embodiment, the monitoring agent 197monitors and measures performance of a browser on the client 102. Insome embodiments, the monitoring agent 197 monitors and measuresperformance of any application delivered via the client agent 120. Inother embodiments, the monitoring agent 197 measures and monitors enduser response times for an application, such as web-based or HTTPresponse times. The monitoring agent 197 may monitor and measureperformance of an ICA or RDP client. In another embodiment, themonitoring agent 197 measures and monitors metrics for a user session orapplication session. In some embodiments, monitoring agent 197 measuresand monitors an ICA or RDP session. In one embodiment, the monitoringagent 197 measures and monitors the performance of the appliance 200 inaccelerating delivery of an application and/or data to the client 102.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

D. Systems and Methods for Providing Virtualized Application DeliveryController

Referring now to FIG. 4A, a block diagram depicts one embodiment of avirtualization environment 400. In brief overview, a computing device100 includes a hypervisor layer, a virtualization layer, and a hardwarelayer. The hypervisor layer includes a hypervisor 401 (also referred toas a virtualization manager) that allocates and manages access to anumber of physical resources in the hardware layer (e.g., theprocessor(s) 421, and disk(s) 428) by at least one virtual machineexecuting in the virtualization layer. The virtualization layer includesat least one operating system 410 and a plurality of virtual resourcesallocated to the at least one operating system 410. Virtual resourcesmay include, without limitation, a plurality of virtual processors 432a, 432 b, 432 c (generally 432), and virtual disks 442 a, 442 b, 442 c(generally 442), as well as virtual resources such as virtual memory andvirtual network interfaces. The plurality of virtual resources and theoperating system 410 may be referred to as a virtual machine 406. Avirtual machine 406 may include a control operating system 405 incommunication with the hypervisor 401 and used to execute applicationsfor managing and configuring other virtual machines on the computingdevice 100.

In greater detail, a hypervisor 401 may provide virtual resources to anoperating system in any manner which simulates the operating systemhaving access to a physical device. A hypervisor 401 may provide virtualresources to any number of guest operating systems 410 a, 410 b(generally 410). In some embodiments, a computing device 100 executesone or more types of hypervisors. In these embodiments, hypervisors maybe used to emulate virtual hardware, partition physical hardware,virtualize physical hardware, and execute virtual machines that provideaccess to computing environments. Hypervisors may include thosemanufactured by VMWare, Inc., of Palo Alto, Calif.; the XEN hypervisor,an open source product whose development is overseen by the open sourceXen.org community; HyperV, VirtualServer or virtual PC hypervisorsprovided by Microsoft, or others. In some embodiments, a computingdevice 100 executing a hypervisor that creates a virtual machineplatform on which guest operating systems may execute is referred to asa host server. In one of these embodiments, for example, the computingdevice 100 is a XEN SERVER provided by Citrix Systems, Inc., of FortLauderdale, Fla.

In some embodiments, a hypervisor 401 executes within an operatingsystem executing on a computing device. In one of these embodiments, acomputing device executing an operating system and a hypervisor 401 maybe said to have a host operating system (the operating system executingon the computing device), and a guest operating system (an operatingsystem executing within a computing resource partition provided by thehypervisor 401). In other embodiments, a hypervisor 401 interactsdirectly with hardware on a computing device, instead of executing on ahost operating system. In one of these embodiments, the hypervisor 401may be said to be executing on “bare metal,” referring to the hardwarecomprising the computing device.

In some embodiments, a hypervisor 401 may create a virtual machine 406a-c (generally 406) in which an operating system 410 executes. In one ofthese embodiments, for example, the hypervisor 401 loads a virtualmachine image to create a virtual machine 406. In another of theseembodiments, the hypervisor 401 executes an operating system 410 withinthe virtual machine 406. In still another of these embodiments, thevirtual machine 406 executes an operating system 410.

In some embodiments, the hypervisor 401 controls processor schedulingand memory partitioning for a virtual machine 406 executing on thecomputing device 100. In one of these embodiments, the hypervisor 401controls the execution of at least one virtual machine 406. In anotherof these embodiments, the hypervisor 401 presents at least one virtualmachine 406 with an abstraction of at least one hardware resourceprovided by the computing device 100. In other embodiments, thehypervisor 401 controls whether and how physical processor capabilitiesare presented to the virtual machine 406.

A control operating system 405 may execute at least one application formanaging and configuring the guest operating systems. In one embodiment,the control operating system 405 may execute an administrativeapplication, such as an application including a user interface providingadministrators with access to functionality for managing the executionof a virtual machine, including functionality for executing a virtualmachine, terminating an execution of a virtual machine, or identifying atype of physical resource for allocation to the virtual machine. Inanother embodiment, the hypervisor 401 executes the control operatingsystem 405 within a virtual machine 406 created by the hypervisor 401.In still another embodiment, the control operating system 405 executesin a virtual machine 406 that is authorized to directly access physicalresources on the computing device 100. In some embodiments, a controloperating system 405 a on a computing device 100 a may exchange datawith a control operating system 405 b on a computing device 100 b, viacommunications between a hypervisor 401 a and a hypervisor 401 b. Inthis way, one or more computing devices 100 may exchange data with oneor more of the other computing devices 100 regarding processors andother physical resources available in a pool of resources. In one ofthese embodiments, this functionality allows a hypervisor to manage apool of resources distributed across a plurality of physical computingdevices. In another of these embodiments, multiple hypervisors manageone or more of the guest operating systems executed on one of thecomputing devices 100.

In one embodiment, the control operating system 405 executes in avirtual machine 406 that is authorized to interact with at least oneguest operating system 410. In another embodiment, a guest operatingsystem 410 communicates with the control operating system 405 via thehypervisor 401 in order to request access to a disk or a network. Instill another embodiment, the guest operating system 410 and the controloperating system 405 may communicate via a communication channelestablished by the hypervisor 401, such as, for example, via a pluralityof shared memory pages made available by the hypervisor 401.

In some embodiments, the control operating system 405 includes a networkback-end driver for communicating directly with networking hardwareprovided by the computing device 100. In one of these embodiments, thenetwork back-end driver processes at least one virtual machine requestfrom at least one guest operating system 110. In other embodiments, thecontrol operating system 405 includes a block back-end driver forcommunicating with a storage element on the computing device 100. In oneof these embodiments, the block back-end driver reads and writes datafrom the storage element based upon at least one request received from aguest operating system 410.

In one embodiment, the control operating system 405 includes a toolsstack 404. In another embodiment, a tools stack 404 providesfunctionality for interacting with the hypervisor 401, communicatingwith other control operating systems 405 (for example, on a secondcomputing device 100 b), or managing virtual machines 406 b, 406 c onthe computing device 100. In another embodiment, the tools stack 404includes customized applications for providing improved managementfunctionality to an administrator of a virtual machine farm. In someembodiments, at least one of the tools stack 404 and the controloperating system 405 include a management API that provides an interfacefor remotely configuring and controlling virtual machines 406 running ona computing device 100. In other embodiments, the control operatingsystem 405 communicates with the hypervisor 401 through the tools stack404.

In one embodiment, the hypervisor 401 executes a guest operating system410 within a virtual machine 406 created by the hypervisor 401. Inanother embodiment, the guest operating system 410 provides a user ofthe computing device 100 with access to resources within a computingenvironment. In still another embodiment, a resource includes a program,an application, a document, a file, a plurality of applications, aplurality of files, an executable program file, a desktop environment, acomputing environment, or other resource made available to a user of thecomputing device 100. In yet another embodiment, the resource may bedelivered to the computing device 100 via a plurality of access methodsincluding, but not limited to, conventional installation directly on thecomputing device 100, delivery to the computing device 100 via a methodfor application streaming, delivery to the computing device 100 ofoutput data generated by an execution of the resource on a secondcomputing device 100′ and communicated to the computing device 100 via apresentation layer protocol, delivery to the computing device 100 ofoutput data generated by an execution of the resource via a virtualmachine executing on a second computing device 100′, or execution from aremovable storage device connected to the computing device 100, such asa USB device, or via a virtual machine executing on the computing device100 and generating output data. In some embodiments, the computingdevice 100 transmits output data generated by the execution of theresource to another computing device 100′.

In one embodiment, the guest operating system 410, in conjunction withthe virtual machine on which it executes, forms a fully-virtualizedvirtual machine which is not aware that it is a virtual machine; such amachine may be referred to as a “Domain U HVM (Hardware Virtual Machine)virtual machine”. In another embodiment, a fully-virtualized machineincludes software emulating a Basic Input/Output System (BIOS) in orderto execute an operating system within the fully-virtualized machine. Instill another embodiment, a fully-virtualized machine may include adriver that provides functionality by communicating with the hypervisor401. In such an embodiment, the driver may be aware that it executeswithin a virtualized environment. In another embodiment, the guestoperating system 410, in conjunction with the virtual machine on whichit executes, forms a paravirtualized virtual machine, which is awarethat it is a virtual machine; such a machine may be referred to as a“Domain U PV virtual machine”. In another embodiment, a paravirtualizedmachine includes additional drivers that a fully-virtualized machinedoes not include. In still another embodiment, the paravirtualizedmachine includes the network back-end driver and the block back-enddriver included in a control operating system 405, as described above.

Referring now to FIG. 4B, a block diagram depicts one embodiment of aplurality of networked computing devices in a system in which at leastone physical host executes a virtual machine. In brief overview, thesystem includes a management component 404 and a hypervisor 401. Thesystem includes a plurality of computing devices 100, a plurality ofvirtual machines 406, a plurality of hypervisors 401, a plurality ofmanagement components referred to variously as tools stacks 404 ormanagement components 404, and a physical resource 421, 428. Theplurality of physical machines 100 may each be provided as computingdevices 100, described above in connection with FIGS. 1E-1H and 4A.

In greater detail, a physical disk 428 is provided by a computing device100 and stores at least a portion of a virtual disk 442. In someembodiments, a virtual disk 442 is associated with a plurality ofphysical disks 428. In one of these embodiments, one or more computingdevices 100 may exchange data with one or more of the other computingdevices 100 regarding processors and other physical resources availablein a pool of resources, allowing a hypervisor to manage a pool ofresources distributed across a plurality of physical computing devices.In some embodiments, a computing device 100 on which a virtual machine406 executes is referred to as a physical host 100 or as a host machine100.

The hypervisor executes on a processor on the computing device 100. Thehypervisor allocates, to a virtual disk, an amount of access to thephysical disk. In one embodiment, the hypervisor 401 allocates an amountof space on the physical disk. In another embodiment, the hypervisor 401allocates a plurality of pages on the physical disk. In someembodiments, the hypervisor provisions the virtual disk 442 as part of aprocess of initializing and executing a virtual machine 450.

In one embodiment, the management component 404 a is referred to as apool management component 404 a. In another embodiment, a managementoperating system 405 a, which may be referred to as a control operatingsystem 405 a, includes the management component. In some embodiments,the management component is referred to as a tools stack. In one ofthese embodiments, the management component is the tools stack 404described above in connection with FIG. 4A. In other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, an identification of a virtual machine406 to provision and/or execute. In still other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, the request for migration of a virtualmachine 406 b from one physical machine 100 to another. In furtherembodiments, the management component 404 a identifies a computingdevice 100 b on which to execute a requested virtual machine 406 d andinstructs the hypervisor 401 b on the identified computing device 100 bto execute the identified virtual machine; such a management componentmay be referred to as a pool management component.

Referring now to FIG. 4C, embodiments of a virtual application deliverycontroller or virtual appliance 450 are depicted. In brief overview, anyof the functionality and/or embodiments of the appliance 200 (e.g., anapplication delivery controller) described above in connection withFIGS. 2A and 2B may be deployed in any embodiment of the virtualizedenvironment described above in connection with FIGS. 4A and 4B. Insteadof the functionality of the application delivery controller beingdeployed in the form of an appliance 200, such functionality may bedeployed in a virtualized environment 400 on any computing device 100,such as a client 102, server 106 or appliance 200.

Referring now to FIG. 4C, a diagram of an embodiment of a virtualappliance 450 operating on a hypervisor 401 of a server 106 is depicted.As with the appliance 200 of FIGS. 2A and 2B, the virtual appliance 450may provide functionality for availability, performance, offload andsecurity. For availability, the virtual appliance may perform loadbalancing between layers 4 and 7 of the network and may also performintelligent service health monitoring. For performance increases vianetwork traffic acceleration, the virtual appliance may perform cachingand compression. To offload processing of any servers, the virtualappliance may perform connection multiplexing and pooling and/or SSLprocessing. For security, the virtual appliance may perform any of theapplication firewall functionality and SSL VPN function of appliance200.

Any of the modules of the appliance 200 as described in connection withFIG. 2A may be packaged, combined, designed or constructed in a form ofthe virtualized appliance delivery controller 450 deployable as one ormore software modules or components executable in a virtualizedenvironment 300 or non-virtualized environment on any server, such as anoff the shelf server. For example, the virtual appliance may be providedin the form of an installation package to install on a computing device.With reference to FIG. 2A, any of the cache manager 232, policy engine236, compression 238, encryption engine 234, packet engine 240, GUI 210,CLI 212, shell services 214 and health monitoring programs 216 may bedesigned and constructed as a software component or module to run on anyoperating system of a computing device and/or of a virtualizedenvironment 300. Instead of using the encryption processor 260,processor 262, memory 264 and network stack 267 of the appliance 200,the virtualized appliance 400 may use any of these resources as providedby the virtualized environment 400 or as otherwise available on theserver 106.

Still referring to FIG. 4C, and in brief overview, any one or morevServers 275A-275N may be in operation or executed in a virtualizedenvironment 400 of any type of computing device 100, such as any server106. Any of the modules or functionality of the appliance 200 describedin connection with FIG. 2B may be designed and constructed to operate ineither a virtualized or non-virtualized environment of a server. Any ofthe vServer 275, SSL VPN 280, Intranet UP 282, Switching 284, DNS 286,acceleration 288, App FW 280 and monitoring agent may be packaged,combined, designed or constructed in a form of application deliverycontroller 450 deployable as one or more software modules or componentsexecutable on a device and/or virtualized environment 400.

In some embodiments, a server may execute multiple virtual machines 406a-406 n in the virtualization environment with each virtual machinerunning the same or different embodiments of the virtual applicationdelivery controller 450. In some embodiments, the server may execute oneor more virtual appliances 450 on one or more virtual machines on a coreof a multi-core processing system. In some embodiments, the server mayexecute one or more virtual appliances 450 on one or more virtualmachines on each processor of a multiple processor device.

E. Systems and Methods for Providing a Multi-Core Architecture

In accordance with Moore's Law, the number of transistors that may beplaced on an integrated circuit may double approximately every twoyears. However, CPU speed increases may reach plateaus, for example CPUspeed has been around 3.5-4 GHz range since 2005. In some cases, CPUmanufacturers may not rely on CPU speed increases to gain additionalperformance. Some CPU manufacturers may add additional cores to theirprocessors to provide additional performance. Products, such as those ofsoftware and networking vendors, that rely on CPUs for performance gainsmay improve their performance by leveraging these multi-core CPUs. Thesoftware designed and constructed for a single CPU may be redesignedand/or rewritten to take advantage of a multi-threaded, parallelarchitecture or otherwise a multi-core architecture.

A multi-core architecture of the appliance 200, referred to as nCore ormulti-core technology, allows the appliance in some embodiments to breakthe single core performance barrier and to leverage the power ofmulti-core CPUs. In the previous architecture described in connectionwith FIG. 2A, a single network or packet engine is run. The multiplecores of the nCore technology and architecture allow multiple packetengines to run concurrently and/or in parallel. With a packet enginerunning on each core, the appliance architecture leverages theprocessing capacity of additional cores. In some embodiments, thisprovides up to a 7× increase in performance and scalability.

Illustrated in FIG. 5A are some embodiments of work, task, load ornetwork traffic distribution across one or more processor coresaccording to a type of parallelism or parallel computing scheme, such asfunctional parallelism, data parallelism or flow-based data parallelism.In brief overview, FIG. 5A illustrates embodiments of a multi-coresystem such as an appliance 200′ with n-cores, a total of cores numbers1 through N. In one embodiment, work, load or network traffic can bedistributed among a first core 505A, a second core 505B, a third core505C, a fourth core 505D, a fifth core 505E, a sixth core 505F, aseventh core 505G, and so on such that distribution is across all or twoor more of the n cores 505N (hereinafter referred to collectively ascores 505.) There may be multiple VIPs 275 each running on a respectivecore of the plurality of cores. There may be multiple packet engines 240each running on a respective core of the plurality of cores. Any of theapproaches used may lead to different, varying or similar work load orperformance level 515 across any of the cores. For a functionalparallelism approach, each core may run a different function of thefunctionalities provided by the packet engine, a VIP 275 or appliance200. In a data parallelism approach, data may be paralleled ordistributed across the cores based on the Network Interface Card (NIC)or VIP 275 receiving the data. In another data parallelism approach,processing may be distributed across the cores by distributing dataflows to each core.

In further detail to FIG. 5A, in some embodiments, load, work or networktraffic can be distributed among cores 505 according to functionalparallelism 500. Functional parallelism may be based on each coreperforming one or more respective functions. In some embodiments, afirst core may perform a first function while a second core performs asecond function. In functional parallelism approach, the functions to beperformed by the multi-core system are divided and distributed to eachcore according to functionality. In some embodiments, functionalparallelism may be referred to as task parallelism and may be achievedwhen each processor or core executes a different process or function onthe same or different data. The core or processor may execute the sameor different code. In some cases, different execution threads or codemay communicate with one another as they work. Communication may takeplace to pass data from one thread to the next as part of a workflow.

In some embodiments, distributing work across the cores 505 according tofunctional parallelism 500, can comprise distributing network trafficaccording to a particular function such as network input/outputmanagement (NW I/O) 510A, secure sockets layer (SSL) encryption anddecryption 510B and transmission control protocol (TCP) functions 510C.This may lead to a work, performance or computing load 515 based on avolume or level of functionality being used. In some embodiments,distributing work across the cores 505 according to data parallelism540, can comprise distributing an amount of work 515 based ondistributing data associated with a particular hardware or softwarecomponent. In some embodiments, distributing work across the cores 505according to flow-based data parallelism 520, can comprise distributingdata based on a context or flow such that the amount of work 515A-N oneach core may be similar, substantially equal or relatively evenlydistributed.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine or VIP of the appliance.For example, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this the approach, the workacross the cores may be divided by function in either a coarse-grainedor fine-grained manner. In some cases, as illustrated in FIG. 5A,division by function may lead to different cores running at differentlevels of performance or load 515.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine of the appliance. Forexample, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this the approach, the workacross the cores may be divided by function in either a coarse-grainedor fine-grained manner. In some cases, as illustrated in FIG. 5Adivision by function may lead to different cores running at differentlevels of load or performance.

The functionality or tasks may be distributed in any arrangement andscheme. For example, FIG. 5B illustrates a first core, Core 1 505A,processing applications and processes associated with network I/Ofunctionality 510A. Network traffic associated with network I/O, in someembodiments, can be associated with a particular port number. Thus,outgoing and incoming packets having a port destination associated withNW I/O 510A will be directed towards Core 1 505A which is dedicated tohandling all network traffic associated with the NW I/O port. Similarly,Core 2 505B is dedicated to handling functionality associated with SSLprocessing and Core 4 505D may be dedicated handling all TCP levelprocessing and functionality.

While FIG. 5A illustrates functions such as network I/O, SSL and TCP,other functions can be assigned to cores. These other functions caninclude any one or more of the functions or operations described herein.For example, any of the functions described in conjunction with FIGS. 2Aand 2B may be distributed across the cores on a functionality basis. Insome cases, a first VIP 275A may run on a first core while a second VIP275B with a different configuration may run on a second core. In someembodiments, each core 505 can handle a particular functionality suchthat each core 505 can handle the processing associated with thatparticular function. For example, Core 2 505B may handle SSL offloadingwhile Core 4 505D may handle application layer processing and trafficmanagement.

In other embodiments, work, load or network traffic may be distributedamong cores 505 according to any type and form of data parallelism 540.In some embodiments, data parallelism may be achieved in a multi-coresystem by each core performing the same task or functionally ondifferent pieces of distributed data. In some embodiments, a singleexecution thread or code controls operations on all pieces of data. Inother embodiments, different threads or instructions control theoperation, but may execute the same code. In some embodiments, dataparallelism is achieved from the perspective of a packet engine,vServers (VIPs) 275A-C, network interface cards (NIC) 542D-E and/or anyother networking hardware or software included on or associated with anappliance 200. For example, each core may run the same packet engine orVIP code or configuration but operate on different sets of distributeddata. Each networking hardware or software construct can receivedifferent, varying or substantially the same amount of data, and as aresult may have varying, different or relatively the same amount of load515.

In the case of a data parallelism approach, the work may be divided upand distributed based on VIPs, NICs and/or data flows of the VIPs orNICs. In one of these approaches, the work of the multi-core system maybe divided or distributed among the VIPs by having each VIP work on adistributed set of data. For example, each core may be configured to runone or more VIPs. Network traffic may be distributed to the core foreach VIP handling that traffic. In another of these approaches, the workof the appliance may be divided or distributed among the cores based onwhich NIC receives the network traffic. For example, network traffic ofa first NIC may be distributed to a first core while network traffic ofa second NIC may be distributed to a second core. In some cases, a coremay process data from multiple NICs.

While FIG. 5A illustrates a single vServer associated with a single core505, as is the case for VIP1 275A, VIP2 275B and VIP3 275C. In someembodiments, a single vServer can be associated with one or more cores505. In contrast, one or more vServers can be associated with a singlecore 505. Associating a vServer with a core 505 may include that core505 to process all functions associated with that particular vServer. Insome embodiments, each core executes a VIP having the same code andconfiguration. In other embodiments, each core executes a VIP having thesame code but different configuration. In some embodiments, each coreexecutes a VIP having different code and the same or differentconfiguration.

Like vServers, NICs can also be associated with particular cores 505. Inmany embodiments, NICs can be connected to one or more cores 505 suchthat when a NIC receives or transmits data packets, a particular core505 handles the processing involved with receiving and transmitting thedata packets. In one embodiment, a single NIC can be associated with asingle core 505, as is the case with NIC1 542D and NIC2 542E. In otherembodiments, one or more NICs can be associated with a single core 505.In other embodiments, a single NIC can be associated with one or morecores 505. In these embodiments, load could be distributed amongst theone or more cores 505 such that each core 505 processes a substantiallysimilar amount of load. A core 505 associated with a NIC may process allfunctions and/or data associated with that particular NIC.

While distributing work across cores based on data of VIPs or NICs mayhave a level of independency, in some embodiments, this may lead tounbalanced use of cores as illustrated by the varying loads 515 of FIG.5A.

In some embodiments, load, work or network traffic can be distributedamong cores 505 based on any type and form of data flow. In another ofthese approaches, the work may be divided or distributed among coresbased on data flows. For example, network traffic between a client and aserver traversing the appliance may be distributed to and processed byone core of the plurality of cores. In some cases, the core initiallyestablishing the session or connection may be the core for which networktraffic for that session or connection is distributed. In someembodiments, the data flow is based on any unit or portion of networktraffic, such as a transaction, a request/response communication ortraffic originating from an application on a client. In this manner andin some embodiments, data flows between clients and servers traversingthe appliance 200′ may be distributed in a more balanced manner than theother approaches.

In flow-based data parallelism 520, distribution of data is related toany type of flow of data, such as request/response pairings,transactions, sessions, connections or application communications. Forexample, network traffic between a client and a server traversing theappliance may be distributed to and processed by one core of theplurality of cores. In some cases, the core initially establishing thesession or connection may be the core for which network traffic for thatsession or connection is distributed. The distribution of data flow maybe such that each core 505 carries a substantially equal or relativelyevenly distributed amount of load, data or network traffic.

In some embodiments, the data flow is based on any unit or portion ofnetwork traffic, such as a transaction, a request/response communicationor traffic originating from an application on a client. In this mannerand in some embodiments, data flows between clients and serverstraversing the appliance 200′ may be distributed in a more balancedmanner than the other approached. In one embodiment, data flow can bedistributed based on a transaction or a series of transactions. Thistransaction, in some embodiments, can be between a client and a serverand can be characterized by an IP address or other packet identifier.For example, Core 1 505A can be dedicated to transactions between aparticular client and a particular server, therefore the load 515A onCore 1 505A may be comprised of the network traffic associated with thetransactions between the particular client and server. Allocating thenetwork traffic to Core 1 505A can be accomplished by routing all datapackets originating from either the particular client or server to Core1 505A.

While work or load can be distributed to the cores based in part ontransactions, in other embodiments load or work can be allocated on aper packet basis. In these embodiments, the appliance 200 can interceptdata packets and allocate them to a core 505 having the least amount ofload. For example, the appliance 200 could allocate a first incomingdata packet to Core 1 505A because the load 515A on Core 1 is less thanthe load 515B-N on the rest of the cores 505B-N. Once the first datapacket is allocated to Core 1 505A, the amount of load 515A on Core 1505A is increased proportional to the amount of processing resourcesneeded to process the first data packet. When the appliance 200intercepts a second data packet, the appliance 200 will allocate theload to Core 4 505D because Core 4 505D has the second least amount ofload. Allocating data packets to the core with the least amount of loadcan, in some embodiments, ensure that the load 515A-N distributed toeach core 505 remains substantially equal.

In other embodiments, load can be allocated on a per unit basis where asection of network traffic is allocated to a particular core 505. Theabove-mentioned example illustrates load balancing on a per/packetbasis. In other embodiments, load can be allocated based on a number ofpackets such that every 10, 100 or 1000 packets are allocated to thecore 505 having the least amount of load. The number of packetsallocated to a core 505 can be a number determined by an application,user or administrator and can be any number greater than zero. In stillother embodiments, load can be allocated based on a time metric suchthat packets are distributed to a particular core 505 for apredetermined amount of time. In these embodiments, packets can bedistributed to a particular core 505 for five milliseconds or for anyperiod of time determined by a user, program, system, administrator orotherwise. After the predetermined time period elapses, data packets aretransmitted to a different core 505 for the predetermined period oftime.

Flow-based data parallelism methods for distributing work, load ornetwork traffic among the one or more cores 505 can comprise anycombination of the above-mentioned embodiments. These methods can becarried out by any part of the appliance 200, by an application or setof executable instructions executing on one of the cores 505, such asthe packet engine, or by any application, program or agent executing ona computing device in communication with the appliance 200.

The functional and data parallelism computing schemes illustrated inFIG. 5A can be combined in any manner to generate a hybrid parallelismor distributed processing scheme that encompasses function parallelism500, data parallelism 540, flow-based data parallelism 520 or anyportions thereof. In some cases, the multi-core system may use any typeand form of load balancing schemes to distribute load among the one ormore cores 505. The load balancing scheme may be used in any combinationwith any of the functional and data parallelism schemes or combinationsthereof.

Illustrated in FIG. 5B is an embodiment of a multi-core system 545,which may be any type and form of one or more systems, appliances,devices or components. This system 545, in some embodiments, can beincluded within an appliance 200 having one or more processing cores505A-N. The system 545 can further include one or more packet engines(PE) or packet processing engines (PPE) 548A-N communicating with amemory bus 556. The memory bus may be used to communicate with the oneor more processing cores 505A-N. Also included within the system 545 canbe one or more network interface cards (NIC) 552 and a flow distributor550 which can further communicate with the one or more processing cores505A-N. The flow distributor 550 can comprise a Receive Side Scaler(RSS) or Receive Side Scaling (RSS) module 560.

Further referring to FIG. 5B, and in more detail, in one embodiment thepacket engine(s) 548A-N can comprise any portion of the appliance 200described herein, such as any portion of the appliance described inFIGS. 2A and 2B. The packet engine(s) 548A-N can, in some embodiments,comprise any of the following elements: the packet engine 240, a networkstack 267; a cache manager 232; a policy engine 236; a compressionengine 238; an encryption engine 234; a GUI 210; a CLI 212; shellservices 214; monitoring programs 216; and any other software orhardware element able to receive data packets from one of either thememory bus 556 or the one of more cores 505A-N. In some embodiments, thepacket engine(s) 548A-N can comprise one or more vServers 275A-N, or anyportion thereof. In other embodiments, the packet engine(s) 548A-N canprovide any combination of the following functionalities: SSL VPN 280;Intranet UP 282; switching 284; DNS 286; packet acceleration 288; App FW280; monitoring such as the monitoring provided by a monitoring agent197; functionalities associated with functioning as a TCP stack; loadbalancing; SSL offloading and processing; content switching; policyevaluation; caching; compression; encoding; decompression; decoding;application firewall functionalities; XML processing and acceleration;and SSL VPN connectivity.

The packet engine(s) 548A-N can, in some embodiments, be associated witha particular server, user, client or network. When a packet engine 548becomes associated with a particular entity, that packet engine 548 canprocess data packets associated with that entity. For example, should apacket engine 548 be associated with a first user, that packet engine548 will process and operate on packets generated by the first user, orpackets having a destination address associated with the first user.Similarly, the packet engine 548 may choose not to be associated with aparticular entity such that the packet engine 548 can process andotherwise operate on any data packets not generated by that entity ordestined for that entity.

In some instances, the packet engine(s) 548A-N can be configured tocarry out the any of the functional and/or data parallelism schemesillustrated in FIG. 5A. In these instances, the packet engine(s) 548A-Ncan distribute functions or data among the processing cores 505A-N sothat the distribution is according to the parallelism or distributionscheme. In some embodiments, a single packet engine(s) 548A-N carriesout a load balancing scheme, while in other embodiments one or morepacket engine(s) 548A-N carry out a load balancing scheme. Each core505A-N, in one embodiment, can be associated with a particular packetengine 548 such that load balancing can be carried out by the packetengine. Load balancing may in this embodiment, require that each packetengine 548A-N associated with a core 505 communicate with the otherpacket engines associated with cores so that the packet engines 548A-Ncan collectively determine where to distribute load. One embodiment ofthis process can include an arbiter that receives votes from each packetengine for load. The arbiter can distribute load to each packet engine548A-N based in part on the age of the engine's vote and in some cases apriority value associated with the current amount of load on an engine'sassociated core 505.

Any of the packet engines running on the cores may run in user mode,kernel or any combination thereof. In some embodiments, the packetengine operates as an application or program running is user orapplication space. In these embodiments, the packet engine may use anytype and form of interface to access any functionality provided by thekernel. In some embodiments, the packet engine operates in kernel modeor as part of the kernel. In some embodiments, a first portion of thepacket engine operates in user mode while a second portion of the packetengine operates in kernel mode. In some embodiments, a first packetengine on a first core executes in kernel mode while a second packetengine on a second core executes in user mode. In some embodiments, thepacket engine or any portions thereof operates on or in conjunction withthe NIC or any drivers thereof

In some embodiments the memory bus 556 can be any type and form ofmemory or computer bus. While a single memory bus 556 is depicted inFIG. 5B, the system 545 can comprise any number of memory buses 556. Inone embodiment, each packet engine 548 can be associated with one ormore individual memory buses 556.

The NIC 552 can in some embodiments be any of the network interfacecards or mechanisms described herein. The NIC 552 can have any number ofports. The NIC can be designed and constructed to connect to any typeand form of network 104. While a single NIC 552 is illustrated, thesystem 545 can comprise any number of NICs 552. In some embodiments,each core 505A-N can be associated with one or more single NICs 552.Thus, each core 505 can be associated with a single NIC 552 dedicated toa particular core 505.

The cores 505A-N can comprise any of the processors described herein.Further, the cores 505A-N can be configured according to any of the core505 configurations described herein. Still further, the cores 505A-N canhave any of the core 505 functionalities described herein. While FIG. 5Billustrates seven cores 505A-G, any number of cores 505 can be includedwithin the system 545. In particular, the system 545 can comprise “N”cores, where “N” is a whole number greater than zero.

A core may have or use memory that is allocated or assigned for use tothat core. The memory may be considered private or local memory of thatcore and only accessible by that core. A core may have or use memorythat is shared or assigned to multiple cores. The memory may beconsidered public or shared memory that is accessible by more than onecore. A core may use any combination of private and public memory. Withseparate address spaces for each core, some level of coordination iseliminated from the case of using the same address space. With aseparate address space, a core can perform work on information and datain the core's own address space without worrying about conflicts withother cores. Each packet engine may have a separate memory pool for TCPand/or SSL connections.

Further referring to FIG. 5B, any of the functionality and/orembodiments of the cores 505 described above in connection with FIG. 5Acan be deployed in any embodiment of the virtualized environmentdescribed above in connection with FIGS. 4A and 4B. Instead of thefunctionality of the cores 505 being deployed in the form of a physicalprocessor 505, such functionality may be deployed in a virtualizedenvironment 400 on any computing device 100, such as a client 102,server 106 or appliance 200. In other embodiments, instead of thefunctionality of the cores 505 being deployed in the form of anappliance or a single device, the functionality may be deployed acrossmultiple devices in any arrangement. For example, one device maycomprise two or more cores and another device may comprise two or morecores. For example, a multi-core system may include a cluster ofcomputing devices, a server farm or network of computing devices. Insome embodiments, instead of the functionality of the cores 505 beingdeployed in the form of cores, the functionality may be deployed on aplurality of processors, such as a plurality of single core processors.

In one embodiment, the cores 505 may be any type and form of processor.In some embodiments, a core can function substantially similar to anyprocessor or central processing unit described herein. In someembodiment, the cores 505 may comprise any portion of any processordescribed herein. While FIG. 5A illustrates seven cores, there can existany “N” number of cores within an appliance 200, where “N” is any wholenumber greater than one. In some embodiments, the cores 505 can beinstalled within a common appliance 200, while in other embodiments thecores 505 can be installed within one or more appliance(s) 200communicatively connected to one another. The cores 505 can in someembodiments comprise graphics processing software, while in otherembodiments the cores 505 provide general processing capabilities. Thecores 505 can be installed physically near each other and/or can becommunicatively connected to each other. The cores may be connected byany type and form of bus or subsystem physically and/or communicativelycoupled to the cores for transferring data between to, from and/orbetween the cores.

While each core 505 can comprise software for communicating with othercores, in some embodiments a core manager (not shown) can facilitatecommunication between each core 505. In some embodiments, the kernel mayprovide core management. The cores may interface or communicate witheach other using a variety of interface mechanisms. In some embodiments,core to core messaging may be used to communicate between cores, such asa first core sending a message or data to a second core via a bus orsubsystem connecting the cores. In some embodiments, cores maycommunicate via any type and form of shared memory interface. In oneembodiment, there may be one or more memory locations shared among allthe cores. In some embodiments, each core may have separate memorylocations shared with each other core. For example, a first core mayhave a first shared memory with a second core and a second share memorywith a third core. In some embodiments, cores may communicate via anytype of programming or API, such as function calls via the kernel. Insome embodiments, the operating system may recognize and supportmultiple core devices and provide interfaces and API for inter-corecommunications.

The flow distributor 550 can be any application, program, library,script, task, service, process or any type and form of executableinstructions executing on any type and form of hardware. In someembodiments, the flow distributor 550 may any design and construction ofcircuitry to perform any of the operations and functions describedherein. In some embodiments, the flow distributor distribute, forwards,routes, controls and/or manage the distribution of data packets amongthe cores 505 and/or packet engine or VIPs running on the cores. Theflow distributor 550, in some embodiments, can be referred to as aninterface master. In one embodiment, the flow distributor 550 comprisesa set of executable instructions executing on a core or processor of theappliance 200. In another embodiment, the flow distributor 550 comprisesa set of executable instructions executing on a computing machine incommunication with the appliance 200. In some embodiments, the flowdistributor 550 comprises a set of executable instructions executing ona NIC, such as firmware. In still other embodiments, the flowdistributor 550 comprises any combination of software and hardware todistribute data packets among cores or processors. In one embodiment,the flow distributor 550 executes on at least one of the cores 505A-N,while in other embodiments a separate flow distributor 550 assigned toeach core 505A-N executes on an associated core 505A-N. The flowdistributor may use any type and form of statistical or probabilisticalgorithms or decision making to balance the flows across the cores. Thehardware of the appliance, such as a NIC, or the kernel may be designedand constructed to support sequential operations across the NICs and/orcores.

In embodiments where the system 545 comprises one or more flowdistributors 550, each flow distributor 550 can be associated with aprocessor 505 or a packet engine 548. The flow distributors 550 cancomprise an interface mechanism that allows each flow distributor 550 tocommunicate with the other flow distributors 550 executing within thesystem 545. In one instance, the one or more flow distributors 550 candetermine how to balance load by communicating with each other. Thisprocess can operate substantially similarly to the process describedabove for submitting votes to an arbiter which then determines whichflow distributor 550 should receive the load. In other embodiments, afirst flow distributor 550′ can identify the load on an associated coreand determine whether to forward a first data packet to the associatedcore based on any of the following criteria: the load on the associatedcore is above a predetermined threshold; the load on the associated coreis below a predetermined threshold; the load on the associated core isless than the load on the other cores; or any other metric that can beused to determine where to forward data packets based in part on theamount of load on a processor.

The flow distributor 550 can distribute network traffic among the cores505 according to a distribution, computing or load balancing scheme suchas those described herein. In one embodiment, the flow distributor candistribute network traffic according to any one of a functionalparallelism distribution scheme 550, a data parallelism loaddistribution scheme 540, a flow-based data parallelism distributionscheme 520, or any combination of these distribution scheme or any loadbalancing scheme for distributing load among multiple processors. Theflow distributor 550 can therefore act as a load distributor by takingin data packets and distributing them across the processors according toan operative load balancing or distribution scheme. In one embodiment,the flow distributor 550 can comprise one or more operations, functionsor logic to determine how to distribute packers, work or loadaccordingly. In still other embodiments, the flow distributor 550 cancomprise one or more sub operations, functions or logic that canidentify a source address and a destination address associated with adata packet, and distribute packets accordingly.

In some embodiments, the flow distributor 550 can comprise areceive-side scaling (RSS) network driver, module 560 or any type andform of executable instructions which distribute data packets among theone or more cores 505. The RSS module 560 can comprise any combinationof hardware and software, In some embodiments, the RSS module 560 worksin conjunction with the flow distributor 550 to distribute data packetsacross the cores 505A-N or among multiple processors in amulti-processor network. The RSS module 560 can execute within the NIC552 in some embodiments, and in other embodiments can execute on any oneof the cores 505.

In some embodiments, the RSS module 560 uses the MICROSOFTreceive-side-scaling (RSS) scheme. In one embodiment, RSS is a MicrosoftScalable Networking initiative technology that enables receiveprocessing to be balanced across multiple processors in the system whilemaintaining in-order delivery of the data. The RSS may use any type andform of hashing scheme to determine a core or processor for processing anetwork packet.

The RSS module 560 can apply any type and form hash function such as theToeplitz hash function. The hash function may be applied to the hashtype or any the sequence of values. The hash function may be a securehash of any security level or is otherwise cryptographically secure. Thehash function may use a hash key. The size of the key is dependent uponthe hash function. For the Toeplitz hash, the size may be 40 bytes forIPv6 and 16 bytes for IPv4.

The hash function may be designed and constructed based on any one ormore criteria or design goals. In some embodiments, a hash function maybe used that provides an even distribution of hash result for differenthash inputs and different hash types, including TCP/IPv4, TCP/IPv6,IPv4, and IPv6 headers. In some embodiments, a hash function may be usedthat provides a hash result that is evenly distributed when a smallnumber of buckets are present (for example, two or four). In someembodiments, hash function may be used that provides a hash result thatis randomly distributed when a large number of buckets were present (forexample, 64 buckets). In some embodiments, the hash function isdetermined based on a level of computational or resource usage. In someembodiments, the hash function is determined based on ease or difficultyof implementing the hash in hardware. In some embodiments, the hashfunction is determined based on the ease or difficulty of a maliciousremote host to send packets that would all hash to the same bucket.

The RSS may generate hashes from any type and form of input, such as asequence of values. This sequence of values can include any portion ofthe network packet, such as any header, field or payload of networkpacket, or portions thereof. In some embodiments, the input to the hashmay be referred to as a hash type and include any tuples of informationassociated with a network packet or data flow, such as any of thefollowing: a four tuple comprising at least two IP addresses and twoports; a four tuple comprising any four sets of values; a six tuple; atwo tuple; and/or any other sequence of numbers or values. The followingare example of hash types that may be used by RSS:

4-tuple of source TCP Port, source IP version 4 (IPv4) address,destination TCP Port, and destination IPv4 address.

4-tuple of source TCP Port, source IP version 6 (IPv6) address,destination TCP Port, and destination IPv6 address.

2-tuple of source IPv4 address, and destination IPv4 address.

2-tuple of source IPv6 address, and destination IPv6 address.

2-tuple of source IPv6 address, and destination IPv6 address, includingsupport for parsing IPv6 extension headers.

The hash result or any portion thereof may be used to identify a core orentity, such as a packet engine or VIP, for distributing a networkpacket. In some embodiments, one or more hash bits or mask are appliedto the hash result. The hash bit or mask may be any number of bits orbytes. A NIC may support any number of bits, such as seven bits. Thenetwork stack may set the actual number of bits to be used duringinitialization. The number will be between 1 and 7, inclusive.

The hash result may be used to identify the core or entity via any typeand form of table, such as a bucket table or indirection table. In someembodiments, the number of hash-result bits are used to index into thetable. The range of the hash mask may effectively define the size of theindirection table. Any portion of the hash result or the hast resultitself may be used to index the indirection table. The values in thetable may identify any of the cores or processor, such as by a core orprocessor identifier. In some embodiments, all of the cores of themulti-core system are identified in the table. In other embodiments, aport of the cores of the multi-core system are identified in the table.The indirection table may comprise any number of buckets for example 2to 128 buckets that may be indexed by a hash mask. Each bucket maycomprise a range of index values that identify a core or processor. Insome embodiments, the flow controller and/or RSS module may rebalancethe network rebalance the network load by changing the indirectiontable.

In some embodiments, the multi-core system 575 does not include a RSSdriver or RSS module 560. In some of these embodiments, a softwaresteering module (not shown) or a software embodiment of the RSS modulewithin the system can operate in conjunction with or as part of the flowdistributor 550 to steer packets to cores 505 within the multi-coresystem 575.

The flow distributor 550, in some embodiments, executes within anymodule or program on the appliance 200, on any one of the cores 505 andon any one of the devices or components included within the multi-coresystem 575. In some embodiments, the flow distributor 550′ can executeon the first core 505A, while in other embodiments the flow distributor550″ can execute on the NIC 552. In still other embodiments, an instanceof the flow distributor 550′ can execute on each core 505 included inthe multi-core system 575. In this embodiment, each instance of the flowdistributor 550′ can communicate with other instances of the flowdistributor 550′ to forward packets back and forth across the cores 505.There exist situations where a response to a request packet may not beprocessed by the same core, i.e. the first core processes the requestwhile the second core processes the response. In these situations, theinstances of the flow distributor 550′ can intercept the packet andforward it to the desired or correct core 505, i.e. a flow distributorinstance 550′ can forward the response to the first core. Multipleinstances of the flow distributor 550′ can execute on any number ofcores 505 and any combination of cores 505.

The flow distributor may operate responsive to any one or more rules orpolicies. The rules may identify a core or packet processing engine toreceive a network packet, data or data flow. The rules may identify anytype and form of tuple information related to a network packet, such asa 4-tuple of source and destination IP address and source anddestination ports. Based on a received packet matching the tuplespecified by the rule, the flow distributor may forward the packet to acore or packet engine. In some embodiments, the packet is forwarded to acore via shared memory and/or core to core messaging.

Although FIG. 5B illustrates the flow distributor 550 as executingwithin the multi-core system 575, in some embodiments the flowdistributor 550 can execute on a computing device or appliance remotelylocated from the multi-core system 575. In such an embodiment, the flowdistributor 550 can communicate with the multi-core system 575 to takein data packets and distribute the packets across the one or more cores505. The flow distributor 550 can, in one embodiment, receive datapackets destined for the appliance 200, apply a distribution scheme tothe received data packets and distribute the data packets to the one ormore cores 505 of the multi-core system 575. In one embodiment, the flowdistributor 550 can be included in a router or other appliance such thatthe router can target particular cores 505 by altering meta dataassociated with each packet so that each packet is targeted towards asub-node of the multi-core system 575. In such an embodiment, CISCO'svn-tag mechanism can be used to alter or tag each packet with theappropriate meta data.

Illustrated in FIG. 5C is an embodiment of a multi-core system 575comprising one or more processing cores 505A-N. In brief overview, oneof the cores 505 can be designated as a control core 505A and can beused as a control plane 570 for the other cores 505. The other cores maybe secondary cores which operate in a data plane while the control coreprovides the control plane. The cores 505A-N may share a global cache580. While the control core provides a control plane, the other cores inthe multi-core system form or provide a data plane. These cores performdata processing functionality on network traffic while the controlprovides initialization, configuration and control of the multi-coresystem.

Further referring to FIG. 5C, and in more detail, the cores 505A-N aswell as the control core 505A can be any processor described herein.Furthermore, the cores 505A-N and the control core 505A can be anyprocessor able to function within the system 575 described in FIG. 5C.Still further, the cores 505A-N and the control core 505A can be anycore or group of cores described herein. The control core may be adifferent type of core or processor than the other cores. In someembodiments, the control may operate a different packet engine or have apacket engine configured differently than the packet engines of theother cores.

Any portion of the memory of each of the cores may be allocated to orused for a global cache that is shared by the cores. In brief overview,a predetermined percentage or predetermined amount of each of the memoryof each core may be used for the global cache. For example, 50% of eachmemory of each code may be dedicated or allocated to the shared globalcache. That is, in the illustrated embodiment, 2 GB of each coreexcluding the control plane core or core 1 may be used to form a 28 GBshared global cache. The configuration of the control plane such as viathe configuration services may determine the amount of memory used forthe shared global cache. In some embodiments, each core may provide adifferent amount of memory for use by the global cache. In otherembodiments, any one core may not provide any memory or use the globalcache. In some embodiments, any of the cores may also have a local cachein memory not allocated to the global shared memory. Each of the coresmay store any portion of network traffic to the global shared cache.Each of the cores may check the cache for any content to use in arequest or response. Any of the cores may obtain content from the globalshared cache to use in a data flow, request or response.

The global cache 580 can be any type and form of memory or storageelement, such as any memory or storage element described herein. In someembodiments, the cores 505 may have access to a predetermined amount ofmemory (i.e. 32 GB or any other memory amount commensurate with thesystem 575). The global cache 580 can be allocated from thatpredetermined amount of memory while the rest of the available memorycan be allocated among the cores 505. In other embodiments, each core505 can have a predetermined amount of memory. The global cache 580 cancomprise an amount of the memory allocated to each core 505. This memoryamount can be measured in bytes, or can be measured as a percentage ofthe memory allocated to each core 505. Thus, the global cache 580 cancomprise 1 GB of memory from the memory associated with each core 505,or can comprise 20 percent or one-half of the memory associated witheach core 505. In some embodiments, only a portion of the cores 505provide memory to the global cache 580, while in other embodiments theglobal cache 580 can comprise memory not allocated to the cores 505.

Each core 505 can use the global cache 580 to store network traffic orcache data. In some embodiments, the packet engines of the core use theglobal cache to cache and use data stored by the plurality of packetengines. For example, the cache manager of FIG. 2A and cachefunctionality of FIG. 2B may use the global cache to share data foracceleration. For example, each of the packet engines may storeresponses, such as HTML data, to the global cache. Any of the cachemanagers operating on a core may access the global cache to servercaches responses to client requests.

In some embodiments, the cores 505 can use the global cache 580 to storea port allocation table which can be used to determine data flow basedin part on ports. In other embodiments, the cores 505 can use the globalcache 580 to store an address lookup table or any other table or listthat can be used by the flow distributor to determine where to directincoming and outgoing data packets. The cores 505 can, in someembodiments read from and write to cache 580, while in other embodimentsthe cores 505 can only read from or write to cache 580. The cores mayuse the global cache to perform core to core communications.

The global cache 580 may be sectioned into individual memory sectionswhere each section can be dedicated to a particular core 505. In oneembodiment, the control core 505A can receive a greater amount ofavailable cache, while the other cores 505 can receiving varying amountsor access to the global cache 580.

In some embodiments, the system 575 can comprise a control core 505A.While FIG. 5C illustrates core 1 505A as the control core, the controlcore can be any core within the appliance 200 or multi-core system.Further, while only a single control core is depicted, the system 575can comprise one or more control cores each having a level of controlover the system. In some embodiments, one or more control cores can eachcontrol a particular aspect of the system 575. For example, one core cancontrol deciding which distribution scheme to use, while another corecan determine the size of the global cache 580.

The control plane of the multi-core system may be the designation andconfiguration of a core as the dedicated management core or as a mastercore. This control plane core may provide control, management andcoordination of operation and functionality the plurality of cores inthe multi-core system. This control plane core may provide control,management and coordination of allocation and use of memory of thesystem among the plurality of cores in the multi-core system, includinginitialization and configuration of the same. In some embodiments, thecontrol plane includes the flow distributor for controlling theassignment of data flows to cores and the distribution of networkpackets to cores based on data flows. In some embodiments, the controlplane core runs a packet engine and in other embodiments, the controlplane core is dedicated to management and control of the other cores ofthe system.

The control core 505A can exercise a level of control over the othercores 505 such as determining how much memory should be allocated toeach core 505 or determining which core 505 should be assigned to handlea particular function or hardware/software entity. The control core505A, in some embodiments, can exercise control over those cores 505within the control plan 570. Thus, there can exist processors outside ofthe control plane 570 which are not controlled by the control core 505A.Determining the boundaries of the control plane 570 can includemaintaining, by the control core 505A or agent executing within thesystem 575, a list of those cores 505 controlled by the control core505A. The control core 505A can control any of the following:initialization of a core; determining when a core is unavailable;re-distributing load to other cores 505 when one core fails; determiningwhich distribution scheme to implement; determining which core shouldreceive network traffic; determining how much cache should be allocatedto each core; determining whether to assign a particular function orelement to a particular core; determining whether to permit cores tocommunicate with one another; determining the size of the global cache580; and any other determination of a function, configuration oroperation of the cores within the system 575.

F. Systems and Methods for Providing a Distributed Cluster Architecture

As discussed in the previous section, to overcome limitations ontransistor spacing and CPU speed increases, many CPU manufacturers haveincorporated multi-core CPUs to improve performance beyond that capableof even a single, higher speed CPU. Similar or further performance gainsmay be made by operating a plurality of appliances, either single ormulti-core, together as a distributed or clustered appliance. Individualcomputing devices or appliances may be referred to as nodes of thecluster. A centralized management system may perform load balancing,distribution, configuration, or other tasks to allow the nodes tooperate in conjunction as a single computing system. Externally or toother devices, including servers and clients, in many embodiments, thecluster may be viewed as a single virtual appliance or computing device,albeit one with performance exceeding that of a typical individualappliance.

Referring now to FIG. 6, illustrated is an embodiment of a computingdevice cluster or appliance cluster 600. A plurality of appliances 200a-200 n or other computing devices, sometimes referred to as nodes, suchas desktop computers, servers, rackmount servers, blade servers, or anyother type and form of computing device may be joined into a singleappliance cluster 600. Although referred to as an appliance cluster, inmany embodiments, the cluster may operate as an application server,network storage server, backup service, or any other type of computingdevice without limitation. In many embodiments, the appliance cluster600 may be used to perform many of the functions of appliances 200, WANoptimization devices, network acceleration devices, or other devicesdiscussed above.

In some embodiments, the appliance cluster 600 may comprise a homogenousset of computing devices, such as identical appliances, blade serverswithin one or more chassis, desktop or rackmount computing devices, orother devices. In other embodiments, the appliance cluster 600 maycomprise a heterogeneous or mixed set of devices, including differentmodels of appliances, mixed appliances and servers, or any other set ofcomputing devices. This may allow for an appliance cluster 600 to beexpanded or upgraded over time with new models or devices, for example.

In some embodiments, each computing device or appliance 200 of anappliance cluster 600 may comprise a multi-core appliance, as discussedabove. In many such embodiments, the core management and flowdistribution methods discussed above may be utilized by each individualappliance, in addition to the node management and distribution methodsdiscussed herein. This may be thought of as a two-tier distributedsystem, with one appliance comprising and distributing data to multiplenodes, and each node comprising and distributing data for processing tomultiple cores. Accordingly, in such embodiments, the node distributionsystem need not manage flow distribution to individual cores, as thatmay be taken care of by a master or control core as discussed above.

In many embodiments, an appliance cluster 600 may be physically grouped,such as a plurality of blade servers in a chassis or plurality ofrackmount devices in a single rack, but in other embodiments, theappliance cluster 600 may be distributed in a plurality of chassis,plurality of racks, plurality of rooms in a data center, plurality ofdata centers, or any other physical arrangement. Accordingly, theappliance cluster 600 may be considered a virtual appliance, grouped viacommon configuration, management, and purpose, rather than a physicalgroup.

In some embodiments, an appliance cluster 600 may be connected to one ormore networks 104, 104′. For example, referring briefly back to FIG. 1A,in some embodiments, an appliance 200 may be deployed between a network104 joined to one or more clients 102, and a network 104′ joined to oneor more servers 106. An appliance cluster 600 may be similarly deployedto operate as a single appliance. In many embodiments, this may notrequire any network topology changes external to appliance cluster 600,allowing for ease of installation and scalability from a singleappliance scenario. In other embodiments, an appliance cluster 600 maybe similarly deployed as shown in FIGS. 1B-2B or discussed above. Instill other embodiments, an appliance cluster may comprise a pluralityof virtual machines or processes executed by one or more servers. Forexample, in one such embodiment, a server farm may execute a pluralityof virtual machines, each virtual machine configured as an appliance200, and a plurality of the virtual machines acting in concert as anappliance cluster 600. In yet still other embodiments, an appliancecluster 600 may comprise a mix of appliances 200 or virtual machinesconfigured as appliances 200. In some embodiments, appliance cluster 600may be geographically distributed, with the plurality of appliances 200not co-located. For example, referring back to FIG. 6, in one suchembodiment, a first appliance 200 a may be located at a first site, suchas a data center and a second appliance 200 b may be located at a secondsite, such as a central office or corporate headquarters. In a furtherembodiment, such geographically remote appliances may be joined by adedicated network, such as a T1 or T3 point-to-point connection; a VPN;or any other type and form of network. Accordingly, although there maybe additional communications latency compared to co-located appliances200 a-200 b, there may be advantages in reliability in case of sitepower failures or communications outages, scalability, or otherbenefits. In some embodiments, latency issues may be reduced throughgeographic or network-based distribution of data flows. For example,although configured as an appliance cluster 600, communications fromclients and servers at the corporate headquarters may be directed to theappliance 200 b deployed at the site, load balancing may be weighted bylocation, or similar steps can be taken to mitigate any latency.

Still referring to FIG. 6, an appliance cluster 600 may be connected toa network via a client data plane 602. In some embodiments, client dataplane 602 may comprise a communication network, such as a network 104,carrying data between clients and appliance cluster 600. In someembodiments, client data plane 602 may comprise a switch, hub, router,or other network devices bridging an external network 104 and theplurality of appliances 200 a-200 n of the appliance cluster 600. Forexample, in one such embodiment, a router may be connected to anexternal network 104, and connected to a network interface of eachappliance 200 a-200 n. In some embodiments, this router or switch may bereferred to as an interface manager, and may further be configured todistribute traffic evenly across the nodes in the application cluster600. Thus, in many embodiments, the interface master may comprise a flowdistributor external to appliance cluster 600. In other embodiments, theinterface master may comprise one of appliances 200 a-200 n. Forexample, a first appliance 200 a may serve as the interface master,receiving incoming traffic for the appliance cluster 600 anddistributing the traffic across each of appliances 200 b-200 n. In someembodiments, return traffic may similarly flow from each of appliances200 b-200 n via the first appliance 200 a serving as the interfacemaster. In other embodiments, return traffic from each of appliances 200b-200 n may be transmitted directly to a network 104, 104′, or via anexternal router, switch, or other device. In some embodiments,appliances 200 of the appliance cluster not serving as an interfacemaster may be referred to as interface slaves.

The interface master may perform load balancing or traffic flowdistribution in any of a variety of ways. For example, in someembodiments, the interface master may comprise a router performingequal-cost multi-path (ECMP) routing with next hops configured withappliances or nodes of the cluster. The interface master may use anopen-shortest path first (OSPF) In some embodiments, the interfacemaster may use a stateless hash-based mechanism for trafficdistribution, such as hashes based on IP address or other packetinformation tuples, as discussed above. Hash keys and/or salt may beselected for even distribution across the nodes. In other embodiments,the interface master may perform flow distribution via link aggregation(LAG) protocols, or any other type and form of flow distribution, loadbalancing, and routing.

In some embodiments, the appliance cluster 600 may be connected to anetwork via a server data plane 604. Similar to client data plane 602,server data plane 604 may comprise a communication network, such as anetwork 104′, carrying data between servers and appliance cluster 600.In some embodiments, server data plane 604 may comprise a switch, hub,router, or other network devices bridging an external network 104′ andthe plurality of appliances 200 a-200 n of the appliance cluster 600.For example, in one such embodiment, a router may be connected to anexternal network 104′, and connected to a network interface of eachappliance 200 a-200 n. In many embodiments, each appliance 200 a-200 nmay comprise multiple network interfaces, with a first network interfaceconnected to client data plane 602 and a second network interfaceconnected to server data plane 604. This may provide additional securityand prevent direct interface of client and server networks by havingappliance cluster 600 server as an intermediary device. In otherembodiments, client data plane 602 and server data plane 604 may bemerged or combined. For example, appliance cluster 600 may be deployedas a non-intermediary node on a network with clients 102 and servers106. As discussed above, in many embodiments, an interface master may bedeployed on the server data plane 604, for routing and distributingcommunications from the servers and network 104′ to each appliance ofthe appliance cluster. In many embodiments, an interface master forclient data plane 602 and an interface master for server data plane 604may be similarly configured, performing ECMP or LAG protocols asdiscussed above.

In some embodiments, each appliance 200 a-200 n in appliance cluster 600may be connected via an internal communication network or back plane606. Back plane 606 may comprise a communication network for inter-nodeor inter-appliance control and configuration messages, and forinter-node forwarding of traffic. For example, in one embodiment inwhich a first appliance 200 a communicates with a client via network104, and a second appliance 200 b communicates with a server via network104′, communications between the client and server may flow from clientto first appliance, from first appliance to second appliance via backplane 606, and from second appliance to server, and vice versa. In otherembodiments, back plane 606 may carry configuration messages, such asinterface pause or reset commands; policy updates such as filtering orcompression policies; status messages such as buffer status, throughput,or error messages; or any other type and form of inter-nodecommunication. In some embodiments, RSS keys or hash keys may be sharedby all nodes in the cluster, and may be communicated via back plane 606.For example, a first node or master node may select an RSS key, such asat startup or boot, and may distribute this key for use by other nodes.In some embodiments, back plane 606 may comprise a network betweennetwork interfaces of each appliance 200, and may comprise a router,switch, or other network device (not illustrated). Thus, in someembodiments and as discussed above, a router for client data plane 602may be deployed between appliance cluster 600 and network 104, a routerfor server data plane 604 may be deployed between appliance cluster 600and network 104′, and a router for back plane 606 may be deployed aspart of appliance cluster 600. Each router may connect to a differentnetwork interface of each appliance 200. In other embodiments, one ormore planes 602-606 may be combined, or a router or switch may be splitinto multiple LANs or VLANs to connect to different interfaces ofappliances 200 a-200 n and serve multiple routing functionssimultaneously, to reduce complexity or eliminate extra devices from thesystem.

In some embodiments, a control plane (not illustrated) may communicateconfiguration and control traffic from an administrator or user to theappliance cluster 600. In some embodiments, the control plane may be afourth physical network, while in other embodiments, the control planemay comprise a VPN, tunnel, or communication via one of planes 602-606.Thus, the control plane may, in some embodiments, be considered avirtual communication plane. In other embodiments, an administrator mayprovide configuration and control through a separate interface, such asa serial communication interface such as RS-232; a USB communicationinterface; or any other type and form of communication. In someembodiments, an appliance 200 may comprise an interface foradministration, such as a front panel with buttons and a display; a webserver for configuration via network 104, 104′ or back plane 606; or anyother type and form of interface.

In some embodiments, as discussed above, appliance cluster 600 mayinclude internal flow distribution. For example, this may be done toallow nodes to join/leave transparently to external devices. To preventan external flow distributor from needing to be repeatedly reconfiguredon such changes, a node or appliance may act as an interface master ordistributor for steering network packets to the correct node within thecluster 600. For example, in some embodiments, when a node leaves thecluster (such as on failure, reset, or similar cases), an external ECMProuter may identify the change in nodes, and may rehash all flows toredistribute traffic. This may result in dropping and resetting allconnections. The same drop and reset may occur when the node rejoins. Insome embodiments, for reliability, two appliances or nodes withinappliance cluster 600 may receive communications from external routersvia connection mirroring.

In many embodiments, flow distribution among nodes of appliance cluster600 may use any of the methods discussed above for flow distributionamong cores of an appliance. For example, in one embodiment, a masterappliance, master node, or interface master, may compute a RSS hash,such as a Toeplitz hash on incoming traffic and consult a preferencelist or distribution table for the hash. In many embodiments, the flowdistributor may provide the hash to the recipient appliance whenforwarding the traffic. This may eliminate the need for the node torecompute the hash for flow distribution to a core. In many suchembodiments, the RSS key used for calculating hashes for distributionamong the appliances may comprise the same key as that used forcalculating hashes for distribution among the cores, which may bereferred to as a global RSS key, allowing for reuse of the calculatedhash. In some embodiments, the hash may be computed with input tuples oftransport layer headers including port numbers, internet layer headersincluding IP addresses; or any other packet header information. In someembodiments, packet body information may be utilized for the hash. Forexample, in one embodiment in which traffic of one protocol isencapsulated within traffic of another protocol, such as lossy UDPtraffic encapsulated via a lossless TCP header, the flow distributor maycalculate the hash based on the headers of the encapsulated protocol(e.g. UDP headers) rather than the encapsulating protocol (e.g. TCPheaders). Similarly, in some embodiments in which packets areencapsulated and encrypted or compressed, the flow distributor maycalculate the hash based on the headers of the payload packet afterdecryption or decompression. In still other embodiments, nodes may haveinternal IP addresses, such as for configuration or administrationpurposes. Traffic to these IP addresses need not be hashed anddistributed, but rather may be forwarded to the node owning thedestination address. For example, an appliance may have a web server orother server running for configuration or administration purposes at anIP address of 1.2.3.4, and, in some embodiments, may register thisaddress with the flow distributor as its internal IP address. In otherembodiments, the flow distributor may assign internal IP addresses toeach node within the appliance cluster 600. Traffic arriving fromexternal clients or servers, such as a workstation used by anadministrator, directed to the internal IP address of the appliance(1.2.3.4) may be forwarded directly, without requiring hashing.

G. Systems and Methods for Monitor Distribution in Multi-Core Systems

The systems and methods described herein are directed towards monitordistribution in multi-core systems. In general overview, the systems andmethods distribute ownership of monitors for services and ownership ofmonitoring of services, each of which may have one or more associatedmonitors, over a plurality of cores. If a core owns or is responsiblefor a monitor for a service, the core may be responsible for sendingprobes to the service according to the monitor and receiving the resultof each probe. If a core owns or is responsible for monitoring of aservice, the core may be responsible for tracking the state of theservice by processing the results of probes sent to the service byitself or other cores. As a result, the workload for monitoring andtracking the state of services may be distributed across the pluralityof cores.

Each core in the plurality of cores may be responsible for monitors forservices, and each core may send probes to the services according to themonitors and receive the results. If a core is not responsible for theservice, the core may send the results of its probes for the service tothe owner core. If a core owns the service, and is thus responsible fortracking the state of the service, the core may determine the state ofthe service. The core may determine the state of the service byprocessing the results of probes for the service. The core may determinethe state of the service by processing the results of probes sent byitself, probes sent by other cores, or both. The owner core may sendmessages to other cores regarding the state of the service or a changein the state. The owner core responsible for the service may beconsidered or referred to as the consolidator of the monitoring for theservice.

A core may be generally described herein as being an owner of a serviceor owning monitoring of a service. If a core owns a service, the core orthe packet processing engine on the core may take responsibility forestablishing and/or maintaining a state of the service for themulti-core system. In another aspect, a core that owns a service may bea core or packet processing engine that is designated as the core or thepacket processing engine of the plurality of cores and/or plurality ofpacket engines of the multi-core system to be responsible for monitoringthe service.

Referring now to FIG. 7A, a block diagram of an appliance 200 using aplurality of monitoring agents on a plurality of cores to monitor aplurality of network services is shown. In brief overview, an appliance200 comprises a plurality of monitoring agents arranged in a table. Eachof the plurality of cores may include a copy of the table, which isdescribed in fuller detail in FIG. 7B. Each of the plurality ofmonitoring agents is assigned to monitor a service. In one embodiment,each of the plurality of monitoring agents may be assigned a weight.Monitoring agents may also be referred to as probes.

Still referring to FIG. 7A, an appliance 200 comprises a plurality ofmonitoring agents or monitors. A monitoring agent may comprise anyprogram, script, daemon, or other computing routine that reports aperformance or operational characteristic of a network service 270 tothe appliance 200. A monitoring agent may communicate with a networkservice 270 once, or on a predetermined frequency, such as every 1 msecor 1 sec. In some embodiments, a monitoring agent may use arequest/reply messaging mechanism or protocol with the server. In otherembodiments, a monitoring agent may have a custom or proprietaryexchange protocol for communicating with the server. In someembodiments, a single monitoring agent may monitor a plurality ofservers. In other embodiments, a plurality of agents may monitor asingle server. In still other embodiments, a plurality of monitoringagents may each monitor a plurality of servers, wherein each of theplurality of servers is monitored by a plurality of monitoring agents.

In the embodiment shown, the one or more monitoring agents areassociated with one or more network services 270. In other embodiments,the one or more monitoring agents may monitor an appliance 200, vServer,network service 270, client, or any other network resource. In oneembodiment, a user specifies a type of network service to associate withthe one or more monitoring agents. In another embodiment, a usercustomizes a monitoring agent. In still another embodiment, a genericmonitoring agent is used. In yet another embodiment, the one or moremonitoring agents determine the response time of the one or more networkservices 270 for responding to a request of one of the following types:ping, transport control protocol (tcp), tcp extended contentverification, hypertext transfer protocol (http), http extended contentverification, hypertext transfer protocol secure (https), https extendedcontent verification, user datagram protocol, domain name service, andfile transfer protocol.

In some embodiments, the one or more monitoring agents areprotocol-specific agents, each agent determining availability for anetwork service of a particular protocol-type. In some embodiments, amonitoring agent determines a response time of a server 106 or networkservice 270 to a TCP request. In one of these embodiments, the agentuses a “TCP/ICMP echo request” command to send a datagram to the networkservice 270, receive a datagram from the network service 270 inresponse, and determine a response time based on the roundtrip time ofthe datagram. In another of these embodiments, the monitoring agentverifies that the response from the network service 270 includedexpected content and did not contain errors.

In other embodiments, a monitoring agent determines availability of anetwork service 270 to a UDP request. In one of these embodiments, theagent uses a “UDP echo” command to send a datagram to the networkservice 270, receive a datagram from the network service 270 inresponse, and determine a response time based on the roundtrip time ofthe datagram. In another of these embodiments, the monitoring agentverifies that the response from the network service 270 includedexpected content and did not contain errors.

In still other embodiments, the monitoring agent determines availabilityof a network service 270 to an FTP request. In one of these embodiments,the monitoring agent sends an FTP command, such as a “get” command or a“put” command, to the network service 270 and determines a time neededby the network service 270 to respond to the command. In another ofthese embodiments, the monitoring agent verifies that the response fromthe network service 270 included expected content, such as contents of afile requested by a “get” command, and did not contain errors.

In yet other embodiments, the monitoring agent determines availabilityof a network service 270 to an HTTP request. In one of theseembodiments, the monitoring agent sends an HTTP command, such as a “get”request for a uniform resource locator (URL) or a file, to the networkservice 270 and determines a time needed by the network service 270 torespond to the request. In another of these embodiments, the monitoringagent verifies that the response from the network service 270 includedexpected content, such as the contents of a web page identified by theURL, and did not contain errors.

In further embodiments, the monitoring agent determines availability ofa network service 270 to a DNS request. In one of these embodiments, themonitoring agent sends a DNS request, such as a dnsquery or nslookup fora known network address, to the server 106 or network service 270 anddetermines a time needed by the server 106 or network service 270 torespond to the request. In another of these embodiments, the monitoringagent verifies that the response from the network service 270 includedexpected content, such as the domain name of a computing device 100associated with the known network address, and did not contain errors.

A monitoring agent may be assigned a weight by a network appliance 200.A weight may comprise an integer, decimal, or any other numericindicator. In some embodiments, a user may configure the weightcorresponding to a given monitoring agent. In some embodiments, allmonitoring agents may be assigned equal weight. In other embodiments, aplurality of monitoring agents may each be assigned different weights.The weights may be assigned to the monitors based on any criteriaindicating relative importance, including without limitation importanceof the monitored service, reliability of the monitoring mechanism, andthe frequency of monitoring.

In one embodiment, a monitoring agent may be assigned a weight based onthe relative importance of the service the appliance monitors. Forexample, if most user requests in a given environment were HTTPrequests, a monitoring agent monitoring HTTP availability of a server106 might be assigned a weight of 10, while a monitoring agentmonitoring FTP availability of a server 106 might be assigned a weightof 3. Or, for example, if an administrator placed a high priority on UDPapplications, a monitoring agent monitoring UDP availability of a servermay be assigned a weight of 20, while a DNS monitoring agent may beassigned a weight of 5.

In some embodiments, an appliance 200 may compute a sum of the weightsof the monitoring agents currently reporting a network service 270 asoperational. For example, if five monitoring agents, each assigned aweight of 30, are monitoring a network service 270, and three of thefive monitoring agents report the network service 270 as available, theappliance may determine the sum of the monitoring agents currentlyreporting the network service 270 as operational to be 90. Or forexample, if only two monitoring agents, one with a weight of 20 and theother with a weight of 40, are reporting a server 106 as available, theappliance may compute the sum of the monitoring agents currentlyreporting a server 106 as operational to be 60.

Referring now to FIG. 7B, a block diagram of an embodiment of a table700 used for monitoring services in a multi-core system is depicted. Thetable 700 may be store on or in communication with a packet processingengine 548. Each packet processing engine 548 may be associated with atable 700. The entries of the tables 700 associated with the packetprocessing engines 548 may include copies of information regarding themonitors.

In brief overview, the table 700 may include entries corresponding tomonitors for services. Each entry may correspond to a monitor. Eachentry in the table 700 may include fields of information associated withthe monitor. The fields of information may include the service name, themonitor name, the activity status of the monitor with respect to thecore, and the next time the monitor is scheduled to send a probe to theservice (also referred to herein as the “probe time”). In someembodiments, the fields of information may include the identity of thecore that owns the service being monitored. In some embodiments, thefields of information may include the identity of the core that owns themonitor. In many embodiments, the fields of information may include theweight assigned to the monitor.

In various embodiments, a packet processing engine 548 may create anentry in the table 700 when the packet processing engine 548 receives aninstruction from the multi-core device 545 to create a monitor for aservice. In some embodiments, the multi-core device 545 may send theinstruction to create a monitor to the packet processing engine 548 thatwill own the monitor. In other embodiments, the multi-core device 545may send the instruction to create the monitor to all the packetprocessing engines 548. In some of these embodiments, each packetprocessing engine 548 may create an entry for the monitor in itsrespective tables 700 according to the instruction. In other of theseembodiments, a packet processing engine 548 may disregard theinstruction to create a monitor if the packet processing engine 548 willnot own the monitor.

The packet processing engine 548 may process the instruction to createthe entry in the table 700. In some embodiments, the packet processingengine 548 may process the instruction via parsing. In some embodiments,the packet processing engine 548 may parse the instruction into theservice name, the monitor name, and the information for the monitoringschedule. In other embodiments, the packet processing engine 548 mayparse the instruction into the service name, the number of monitors forthe service, and information for the monitoring schedules. In manyembodiments, the packet processing engine 548 may create a new entry inthe table 700 and store the service name and the monitor name. Inadditional embodiments, the packet processing engine 548 may createmultiple entries according to the number of monitors for the service,according to the instruction. In these embodiments, the packetprocessing engine 548 may store, for each entry, the service name and amonitor name chosen according to a predetermined method. In manyembodiments, the packet processing engine 548 may store, for each entry,the information for the monitoring schedule. In additional embodiments,the packet processing engine 548 may store, for any entry, anyinformation obtained by further parsing of the instruction.

The packet processing engine 548 may access the information for themonitoring schedule stored for an entry to calculate a next probe timefor a monitor. The packet processing engine 548 may then store the nextprobe time for the monitor. In many embodiments, the information for themonitoring schedule may include a frequency of monitoring. In variousembodiments, the information for the monitoring schedule may include aformula to calculate the next probe time. In some embodiments, uponsending a probe to a service, the packet processing engine 548 maycalculate the next probe time and overwrite the obsolete probe time forthe entry. In other embodiments, the packet processing engine 548 maydelete the entry and create a new entry for the monitor with the nextprobe time.

The packet processing engine 548 may determine the owner of the monitoraccording to a predetermined algorithm, as described in further detailbelow. The packet processing engine 548 may configure the activitystatus of the monitor with respect to the core according to thedetermination. If the packet processing engine 548 determines the coreowns the monitor, the activity status of the monitor may be set to“schedulable.” As a result, the packet processing engine 548 schedulesprobes for the service according to the monitor's activity status. Ifthe packet processing engine 548 determines the core does not own themonitor, the activity status of the monitor may be set to“non-schedulable.” As a result, the packet processing engine 548 doesnot schedule probes for the service according to the monitor's activitystatus.

Referring now to FIG. 7C, a flow diagram depicting an embodiment ofsteps of a method for configuring a table used for monitoring servicesin a multi-core system is shown and described. In brief overview, themethod includes establishing (step 701) a configuration for monitors.The configuration may identify a plurality of monitors to monitor one ormore services managed by a plurality of packet processing enginesoperating on each of the plurality of cores. The method further includesidentifying (step 703) for each of the plurality of packet processingengines, from the configuration, a monitor name and service name foreach monitor of the plurality of monitors. The method further includescomputing (step 705), by each of the plurality of packet processingengines, for each monitor of the plurality of monitors a value based ona function of the monitor name and the service name. The method furtherincludes determining (step 707), by each of the plurality of packetprocessing engines, a packet processing engine from the plurality ofpacket processing engines to establish the monitor for the service basedon the value corresponding to an identifier of the packet processingengine. Although the steps are described with respect to one packetprocessing engine operating on one core, methods for configuring tablesby each of the packet processing engines would be apparent to one ofordinary skill in the art.

In further detail, at step 701, the packet processing engine 548 mayestablish the configuration for monitors by allocating memory andcreating a table for the monitors. The packet processing engine 548 maycreate entries for the table in response to instructions from themulti-core device to create monitors for services. The packet processingengine 548 may process the instructions to obtain the fields for theentries. For example, the packet processing engine 548 may parse aninstruction to obtain the service name and the monitor name.

The multi-core system may use any type and form of monitor configurationto establish one or more monitors. The configuration may be establishedvia a set of one or more commands or instructions, such as a set ofcommands received via the graphical user interface (GUI) 210 or thecommand line interface (CLI) 212, as described in FIG. 2A. In someembodiments, the packet processing engine 548 may parse an instructionof a configuration to determine a type of monitor. In some embodiments,the packet processing engine 548 may parse an instruction to determine atype of monitor. For example, the packet processing engine 548 maydetermine that the monitor probes the state of a service, a leastresponse time of a service, a dynamic response time of the service, orany other characteristic of the service. In additional embodiments, thepacket processing engine 548 may parse the instruction to obtain theweight of the monitor. The packet processing engine 548 may parse aninstruction to obtain information for a monitoring schedule. The packetprocessing engine 548 may use the information for the monitoringschedule to calculate the next probe time. In any of these embodiments,the packet processing engine 548 may store in an entry any of theinformation obtained by parsing an instruction to create monitor or anyinformation derived from the parsing.

The packet processing engine 548 may establish the entries of the table700 in any order. In some embodiments, the packet processing engine 548establishes entries in the order that the packet processing engine 548receives instructions to create the monitors. In other embodiments, thepacket processing engine 548 establishes entries in order of the serviceand monitor names. In further embodiments, the packet processing engine548 establishes entries in order of the probe times. In someembodiments, the packet processing engine 548 establishes entriesaccording to ownership of the monitors. For example, the packetprocessing engine 548 may group monitors the packet processing engine548 owns apart from the monitors that belong to other cores.

At step 703, the packet processing engine 548 may identify configurationinformation for each monitor. In some embodiments, the packet processingengine 548 may identify a monitor name and a service name for eachmonitor from fields in the entry for each monitor. The packet processingengine 548 may load copies of the monitor and service names into abuffer for additional processing. The packet processing engine mayidentify other configuration information for each monitor as identifiedin table 700. In various embodiments, the packet processing engine 548may identify the type of monitor, the weight of the monitor, theidentity of the core that owns the monitor, the identity of the corethat owns the service associated with the monitor, or any otherconfiguration information.

At step 705, for each monitor, the packet processing engine 548 maycompute a value based on any configuration information for a monitor. Insome embodiments, the packet processing engine 548 may compute a valueusing a function of the monitor name and service name. In variousembodiments, the monitor name may be an identifier of a monitor. In manyembodiments, the service name may be an identifier of a service. Innumerous embodiments, the packet processing engine 548 may compute avalue based on a function of any configuration information, such as themonitor name, service name, type of monitor, weight of the monitor,identity of the core that owns the monitor, identity of the core thatowns the service associated with the monitor, or any combinationthereof. The function or the result of the function may be used toidentify the owner of the monitor. The result may be used as a lookup orindex into a table that identifies cores. The function may be a hashfunction that identified an index into an indirection table to selectthe core. As a result, the value may correspond to an identifier of apacket processing engine. The packet processing engine 548 may computethe value using any function that results in a desired distribution ofmonitor ownership among the packet processing engines 548. The packetprocessing engine 548 may compute the value using copies of the monitorname, service name, or any other configuration information loaded into abuffer.

In some embodiments, the packet processing engine 548 computes the valueaccording to the sums of the ASCII values of the monitor and servicenames. In these embodiments, the packet processing engine 548 may addthe sum of ASCII values of the monitor name to the sum of ASCII valuesof the service name. In one of these embodiments, the packet processingengine 548 may divide this sum by the number of packet processingengines. In another of these embodiments, the packet processing engine548 may perform a modulo operation upon the sum according to the numberof packet processing engines. In further embodiments, the packetprocessing engine 548 may create a variable that stores the number ofmonitors that have been created. In these embodiments, the packetprocessing engine 548 may add the sum of the ASCII values of the servicename to the number of created monitors. The packet processing engine 548may then divide the sum by the number of packet processing engines orperform a modulo operation according to the number of packet processingengines. After the packet processing engine 548 computes the value, thepacket processing engine 548 may increment the variable to account forthe newly created monitor.

The packet processing engine 548 may determine the packet processingengine to establish the monitor for the service based on the computedvalue. In some embodiments, the packet processing engine 548 may comparethe computed value to a value assigned to the packet processing engine548 upon boot-up, wherein the value indicates the packet processingengine 548's order among the plurality of packet processing engines. Inother embodiments, the packet processing engine 548 may compare thecomputed value to an identifier of the packet processing engine 548. Ifthe comparison indicates the packet processing engine 548 owns themonitor, the packet processing engine 548 sets the activity status ofthe monitor to “schedulable.” As a result, the packet processing engine548 will schedule probes for the service according to the monitor. Ifthe comparison indicates that the packet processing engine 548 does notown the monitor, the packet processing engine 548 sets the activitystatus of the monitor to “non-schedulable.” As a result, the packetprocessing engine 548 does not schedule probes for the service, althoughthe information for the monitor will remain in the table 700.

Referring now to FIG. 7D, a flow diagram depicting steps of anembodiment of a method for monitoring services in a multi-core system isshown and described. In brief overview, the method includes sendingprobes to monitor services according to iterations through the entriesof the table 700. For one iteration through the table 700, the methodincludes initializing variables (step 711) associated with the services.The method further includes initializing (step 713) a list of serviceswith significant probe results. The method further includes sending(step 715) a probe to a service according to the ownership of a monitorand the probe time. The method further includes receiving and processing(step 717) the result of the probe. The method further includesdetermining (step 719) if probes have been sent for all the entries inthe table 700. The method further includes sending (step 721)information regarding the results of the probes to services owned byother packet processing engines.

For each iteration through the table 700, the packet processing engine548 may initialize variables associated with the services. A variablemay be related to the results of probes for a service. A variable mayindicate a change in state for a service. The packet processing engine548 may create and initialize the variables when the multi-core device545 boots up. In this embodiment, the packet processing engine 548 mayinitialize the variables at the beginning of each iteration through thetable 700. In other embodiments, the packet processing engine 548 mayinitialize the variables at the end of each iteration through the table700.

The packet processing engine 548 may send a probe to a service accordingto the ownership of a monitor and the probe time. The packet processingengine 548 may examine activity status of the monitor to determine ifthe packet processing engine 548 owns the monitor. If the activitystatus is “non-schedulable,” the packet processing engine 548 does notown the monitor. The packet processing engine 548 then examines theactivity status for the next entry in the table 700. In this manner, thepacket processing engine 548 continues examining the entries in thetable 700 until the packet processing engine 548 encounters a monitorthat the packet processing engine 548 owns. When the packet processingengine 548 encounters a monitor that the packet processing engine 548owns, the packet processing engine 548 compares the scheduled probe timefor the monitor with a signal from a clock. If the scheduled probe timeis less than or equal to the signal from the clock, the packetprocessing engine 548 creates a probe according to the monitor and sendsthe probe to the service. The packet processing engine 548 may calculatethe next probe time and overwrite the probe time field of the entry withthe newly calculated probe time. The packet processing engine 548 maythen continue examining the activity statuses and probe times of entriesin the table 700 until the packet processing engine 548.

With the examining of activity statuses and probe times and sending ofprobes, the packet processing engine 548 may receive and process theresult of a probe. The packet processing engine 548 may use the resultof a probe to adjust a variable associated with a service. In someembodiments, the packet processing engine 548 may increment or decrementthe variable according to the result of a probe. For example, if theprobe indicates a service is “up,” the packet processing engine 548 mayincrement the variable, but if the probe indicates a service is “down,”the packet processing engine 548 may decrement the variable. In someembodiments, the magnitude of the increment or decrement is apredetermined value. In other embodiments, the magnitude of theincrement or decrement depends on the result of the probe.

After adjusting the variable, the packet processing engine 548 maydetermine if the packet processing engine 548 owns the service beingmonitored. If the packet processing engine 548 owns the service, thepacket processing engine 548 may use the variable to update the state ofthe service, as described in FIG. 7E. If the packet processing engine548 does not own the service, the packet processing engine 548 evaluatesthe variable associated with the service to determine if the packetprocessing engine 548 needs to report the results of the probe to theowner packet processing engine 548. In some embodiments, the packetprocessing engine 548 may compare the variable with a predeterminedthreshold. If the variable is greater than the threshold, the packetprocessing engine 548 may determine if the service is already includedin the list of services with probe results. If the service is not in thelist, the packet processing engine 548 may add the service to the list.If the variable is less than the threshold, the packet processing engine548 may remove the service from the list.

After the packet processing engine 548 finishes sending probes andprocessing the results for the entries in the table 700, the packetprocessing engine 548 may send information regarding the results of theprobes to services owned by other packet processing engines. In manyembodiments, the packet processing engine 548 may examine the list ofservices with probe results. For each service in the list, the packetprocessing engine 548 may prepare a message with the service name andthe value of the variable associated with the service. The packetprocessing engine 548 may send the message to the packet processingengine that owns the service. The packet processing engine 548 maydelete the service from the list. In some embodiments, the packetprocessing engine 548 deletes the service after sending the message tothe packet processing engine that owns the service. In otherembodiments, the packet processing engine 548 deletes all the servicesfrom the list after all the messages with variables for the serviceshave been sent to the respective packet processing engines. The packetprocessing engine 548 returns to (step 711) to process another iterationthrough the table 700.

Referring now to FIG. 7E, a flow diagram depicting steps of anembodiment of a method for updating the state of a service in amulti-core system is shown and described. The method includes receivingand processing (step 731) by a packet processing engine 548 that owns aservice (also referred to herein as “owner packet processing engine”)the probe results for the service from other packet processing engines.In some embodiments, the owner packet processing engine 548 receives amessage from another packet processing engine. The message may include aservice name and a value of a variable associated with the service. Thevalue of the variable may reflect the results of probes sent to theservice by the packet processing engine that sent the message. The ownerpacket processing engine may update a variable associated with the stateof a service according to the value in the message. In some embodiments,the owner packet processing engine may add the value in the message tothe variable associated with the state of the service, and in otherembodiments, the owner packet processing engine may subtract the value.

The method also includes determining (step 733) if the state of aservice has changed. In some embodiments, the owner packet processingengine determines if the state of a service has changed by comparing thevariable associated with the state of the service to a predeterminedthreshold. In some embodiments, the owner packet processing enginedetects if the variable was previously less than the threshold and theupdated owner packet processing engine exceeds the threshold. In otherembodiments, the owner packet processing engine detects if the variablepreviously exceeded the threshold and the updated variable is less thanthe threshold.

The method also includes sending (step 735) messages about the new stateof the service to the other packet processing engines. In someembodiments, in response to the detection, the owner packet processingengine creates a message including the state of the service, accordingto the updated variable. The owner packet processing engine may send themessage to all of the other packet processing engines. In otherembodiments, in response to the detection, the owner packet processingengine places the service in a list of services whose statuses havechanged. In these embodiments, the owner packet processing engine maycreate and send messages regarding the states of the services in thelist on a predetermined basis. For example, the owner packet processingengine may create and send the messages according to a predeterminedfrequency, and then delete all the services from the list.

An example of monitor distribution in a multi-core system is hereindescribed. In this example, the multi-core system has 8 cores andmonitors 4 services. The multi-core system is configured to have 20monitors that monitor the 4 services, and 5 monitors are dedicated toeach service. The multi-core system establishes service names andmonitor names for each of the 20 monitors. The multi-core system maycompute a hash value for each monitor based on the service and monitornames. The hash value may determine which core owns a monitor and isresponsible for sending probes to the service according to the monitor.In this example, a hash value may fall between 0 and 8000. If the hashvalue falls between 0 and 999, core 1 owns the monitor. If the hashvalue falls between 1000 and 1999, core 2 owns the monitor, and so on.In this example, core 1 owns the first service, and the hash values forthe monitors determine that cores 1, 2, 5, 6, and 8 own the monitors forthe first service. Core 3 owns the second service, and the hash valuesfor the monitors determine that cores 2, 3, 4, 6, and 7 own the monitorsfor the second service. Core 5 owns the third service, and the hashvalues for the monitors determine that cores 1, 3, 4, 5, and 8 own themonitors for the third service. Core 7 owns the fourth service, and thehash values for the monitors determine that cores 2, 4, 5, 7, and 8 ownthe monitors for the fourth service.

Each core in the multi-core system includes a table that stores entriesfor all 20 monitors. Each core sets the activity statuses for entries to“schedulable” for the monitors it owns and “unschedulable” for themonitors it does not own. In one example, core 1 sets the activitystatuses for its monitors for the first and third services to“schedulable,” but sets activity statuses for all other monitors in itstable to “unschedulable.” In another example, core 2 sets the activitystatuses for its monitors for the second and fourth services to“schedulable,” but sets activity statuses for all other monitors in itstable to “unschedulable.” The remaining cores set the activity statusesfor monitors in its table in the same manner.

If a monitor is set to “schedulable,” a core may send probes accordingto the monitor to the service. The core may receive the results of theprobes. If the core does not own the service, the core may send amessage including the results of the probes to the owner core. Forexample, core 1 may send the results of its probes for the third serviceto core 5. In another example, core 4 may send the results of its probesfor the second service to core 3, the results of its probes for thethird service to core 5, and the results of its probes for the fourthservice to core 7.

If a core does own a service, the core may determine the state of theservice according to results of the probes for the service. The core maydetermine the state by processing the results of its own probes orresults sent from other cores. For example, core 1 may process theresults of its probes for the first service to update the state. Core 1may also process the results of probes sent from cores 2, 5, 6, and 8 toupdate the state of the first service. In another example, core 5 mayprocess the results of its probes for the third service to update thestate. Core 5 may also process the results of probes sent from cores 1,3, 4, and 8 to update the state of the third service. In any of theseexamples, once a core has updated the state of a service it owns, thecore may send a message to the other cores regarding the state of theservice.

H. Systems and Methods for Monitor Distribution in Cluster Systems

The systems and methods of the present solution illustrated in FIGS.8A-9C are directed to monitoring in a cluster system. The systems andmethods distribute the monitors for a service and the ownership of aservice across a cluster system comprising a plurality of nodes. Thenodes in the cluster can be configured to have different sets of virtualservers and services. The ownership and monitoring of the services canbe distributed among all the nodes in the cluster.

Referring now to FIG. 8A, a block diagram of an appliance 200 using aplurality of nodes 801 to monitor a plurality of network services in acluster system is shown. The appliance 200 may be a multi-core applianceor multi-node set of appliances in a cluster system 800. A node 801 maybe a connection point in a cluster system 800. Nodes 801 may be capableof receiving, transmitting and/or forwarding information over a network.In the embodiment shown, the one or more nodes 801 may be associatedwith one or more network services 821. In other embodiments, the one ormore nodes 801 may monitor an appliance 200, vServer, network service821, client, or any other network resource. Although illustrated on aseparate server 106, in many embodiments each node 801 a-801 n withinthe cluster may execute one or more services 821 a-821 c. For example, afirst service 821 a may be executed on a first node 801 a (and monitoredby a first monitor 802 a), or a second service 821 b may be executed onboth a first and second node 801 a and 801 b, such as a distributeddatabase service (and monitored by a monitor 802, 804 on each device,with one monitor designated as an “owner” of the service, as discussedin more detail below).

In one embodiment, a node 801 comprises a plurality of monitoring agents802, 804, 806. The monitoring agents 802, 804, 806 may be bound to anetwork service 821. A monitoring agent 802, 804, 806 may comprise anapplication, service, server, daemon, routine, subroutine, or otherexecutable logic for monitoring performance, load balancing, latency,status, or other information of a service, vserver, or applicationprovided by a server 106 and/or cluster 800.

In yet other embodiments, the monitoring agent determines availabilityof a network service 821 to an HTTP request. In one of theseembodiments, the monitoring agent sends an HTTP command, such as a “get”request for a uniform resource locator (URL) or a file, to the networkservice 821 and determines a time needed by the network service 270 torespond to the request. In another of these embodiments, the monitoringagent verifies that the response from the network service 821 includedexpected content, such as the contents of a web page identified by theURL, and did not contain errors.

Cluster 800 may be a network of appliances 200 working together in asingle system. In some embodiments, the appliances may be referred to asnodes 801. In the cluster 800 system, network traffic may be distributedamong the nodes 801 to provide load balancing in the system. The nodes801 may communicate amongst each other. In some embodiments, when a node801 is added or removed from the cluster 800, the load in the clustermay be redistributed among the nodes 801 still active in the cluster800.

In some embodiments, the service 821 is a daemon process or networkdriver for listening, receiving and/or sending communications for anapplication, such as email, database or an enterprise application. Insome embodiments, the service 821 may communicate on a specific IPaddress, or IP address and port.

Referring now to FIG. 8B, an embodiment of a flow diagram of anembodiment of a method 830 for distributed monitoring of one or moreservices across a plurality of nodes in a cluster system. At step 831,the method includes identifying, by a PE in a cluster system, a servicein the cluster system. At step 833, the method also includesdetermining, by the PE, a master node for the service based upon a hashvalue associated with the node. At step 835, the method further includestransmitting, by the master node, a service state update of the serviceto the other nodes in the cluster system.

In some embodiments, the distribution may be done at a service levelrather than at a monitor level. This design, in some embodiments, mayhelp to reduce the number of probe status updates from different nodesin the cluster to the to the monitoring master. In an embodiment, thedistribution may be done using a probable record linkage technique(sometimes referred to as “PRL”) module, the module based on aconsistent hashing algorithm.

Referring to step 833 in more detail, each of the nodes in the clustercan determine a service, from a plurality of services, to be monitoredby the corresponding node. The determined node can monitor the servicefor the cluster of nodes. The determined node may be referred to as amaster node for the service it is monitoring. In an embodiment, the nodeis selected to monitor the service based on a hash of an identity of theservice in the configuration for the cluster. In some embodiments, aservice unique ID hash may be used to determine the master node for aservice 821. In an embodiment, each node may identify ownership of aservice to monitor based on the hash identity of service including aname of the service configured in the configuration for the cluster. ThePRL module may use the service unique ID hash to determine the masternode for a service 821. Once the master node has been determined, insome embodiments, the master node may begin probing the service. Instill other embodiments, the master node may begin probing the serviceresponsive to receiving a “add service” command from a PE in the clustersystem. In further embodiments, once the “add service” command has beenreceived a new field may be added to update the server information andto store the unique entity ID which will be obtained from theconfiguration system process.

In some embodiments, each node establishes, responsive to thedetermination to monitor a service, a monitor for each service to bemonitored by the node. Each of the nodes may establish a master monitoramong the plurality of monitors established on the node. The master nodemay be selected to monitor the service for the node. In an embodiment,the master monitor can update the remaining monitors on the node withthe status of the service. Within the node 801, the monitor bindings maybe distributed among the processing engines. The non-master nodes(sometimes referred to as non-owner nodes or slave nodes) may set a“don't probe” bit in all the mapped ID address (sometimes referred to asMIPS) associated with the service in all the processing engines so thatthe non-master nodes do not probe the service at all.

In some embodiments, each node 801 may monitor set of services 821 itowns or are assigned to it according to a hash of information about theservices 821, all of the services 821 it owns, or at least one of theservices 821 it owns. Each node 821 may use the existing service statesynchronization (hereinafter referred to as “SSS”) mechanism to updatethe service state and layer 2 information of the service in the clustersystem. In some embodiments, a first monitor on a first node in thecluster of nodes can identify a status of a service to be monitored bythe cluster. The monitor for a service may be referred to as a mastermonitor, a first monitor, or a master packet engine.

Whenever the service state changes for a service or the monitoring ownerof the service changes, in some embodiments, the master node's masterpacket engine (PE0) may create a new SSS instance and populate it withthe layer 2 information and service state information. The unique entityID from the corresponding server information may be copied to a newmember entity ID, which may be added in the SSS data structure. Infurther embodiments, the copied unique entity ID may be used to find thecorresponding service's server information on the receiving end.

In some embodiments, the master node may stop the old (previous) masternode from monitoring the service by adding a new field to the SSS data.The new field may include data indicating the new master node 801 for aservice for all the nodes 801 in the cluster system. In still otherembodiments, a new hash table may be added for efficient searching. Thenew hash table may include a function (entity ID) which can be used asan input to a hashing function and the entry ID may provide an indicatorfor server information. In further embodiments, the entries may be addedinto the hash table in at least one of the following scenarios: addingof a service 821 or domain based service, and adding of a service groupmember. In other embodiments, the entries may be removed from the hashtable in at least one of the following scenarios: removing of a service821 or domain based service, and removing of a service group member.

The master node or PE0 may add the SSS data to a queue, for example aglobal list. In an embodiment, the first monitor on the first node maytransmit to each node in the cluster a message (e.g., SSS data)including the status of the service. In some embodiments, the SSS datamay be broadcast to all the nodes 801 which own the service 821. In oneembodiment, the maximum number of SSS entries supported may be 25K. Instill other embodiments, the maximum number of SSS entries supported maybe 70K. In still other embodiments, any number of entries may besupported.

In some embodiments, a PE in a cluster system, may check whether thereis any SSS entry present in the global list. In still other embodiments,an application programming interface (API) may check every 10 ms. Infurther embodiments, if SSS entries are present on the global list, thePE may notify the nodes which own those particular services or servicegroups. The master node, in some embodiments, may broadcast the SSSentries to the owner nodes using a node to node messaging (NNM)interface or protocol.

In some embodiments, the SSS updates will be transmitted using the NNMservice based upon a priority level in the NNM layer. In one embodiment,the highest priority bit set in the NNM layer may have the highestpriority level. Upon receiving the SSS update, in some embodiments,three conditions must be verified before updating the services serverinformation: whether server information is present; whether the “addservice” command has been receive and whether SSS update is from thecurrent master node, as discussed in more detail below.

The first condition to be verified may be whether the server informationis present in the node 801. In some embodiments, to find the serverinformation entry corresponding to the received SSS entry, the packetengine may search the hash table. If the server information is found inthe node 801 and the first condition is met, then the packet engine maymove on to verify the second condition. If the server information is notfound in the node 801, then the packet engine may cache the SSS entry orstore the SSS entry in a cache memory.

The second condition may be verifying that the “add service” command wasreceived. In some embodiments, the “add service” command should havebeen received and processed by all the PEs in the node. To verify thatthe “add service” command has been received, the server informationreference count may be checked. In further embodiments, if all the PEshave received and processed the “add service” command, the PE may checkif the third condition, whether the SSS update was sent by the currentmaster node, is met. If not, the SSS entry may be cached.

In an embodiment, the master monitor may compare a service identity in aserver database to a unique identity in the service state update toconfirm the monitor is a current monitor for the service. In someembodiments, to determine if the third condition has been met, the PEmay compare the view ID stored in the server information against theview ID received from the master node 801 in the SSS update. If the viewID in the server information is greater than the view ID in the receivedmessage than the message did not come from the current master node andis obsolete. In this case, the SSS message may be ignored. If the viewID in the server information is less than or equal to the view ID in thereceived message, the SSS message will be used to update the serverinformation. In some embodiments, comparing the view ID of the serverinformation to the view ID of the received message may handle issuesthat arise when a node receives both an “add service” command and aserver information update message. In further embodiments, the serverinformation update may be received by a node before the node hasreceived the “add service” command. By caching the server update, thenode 801 can wait to update the service information until the “addservice” command has been received.

In some embodiments, to determine whether the local node is the old orprevious monitoring owner of the service, a comparison between the SSSmonitor's view ID and the server information view ID is performed. Ifthe SSS's monitor view ID comes out to be greater than the serverinformation's master monitor view ID, then the local node is the old orprevious master. If it is determined that the local node is the oldmaster node, the master node flag on the local node may need to be resetto disable monitoring.

In some embodiments, once all three conditions have been met, the PE maysend out a core to core messaging (C2C) broadcast of the received SSSentry that was sent to all the PEs. In one example, without limitation,a SSS entry for clustering is illustrated below:

typedef struct sssdata { NS_CLIST_ENTRY(sssdata) session_list; /* Can beused for free sessions list */ struct { u16bits vlan;   /* 2 bytes */u16bits mss; // mss of the peer u08bitsetheraddr[NSAPI_ETHER_ADDR_LEN];/* ethernet MAC address */ u08bits chan;  /* 1 byte */ u08bits reserved; } l2_params; u16bits port; //servicegroup member port u08bits state; //state of the entity u08bitsnamelen; ssstypes_t st; u32bits ip; u32bits ttl; // dbs resolved ip ttlu32bits delta_probe_ticks; u32bits time; ipv6_128_addr_t ipv6addr; charsg_dbs_server_name[SERVER_UFN]; u32bits flags; /* View id of the MOSwhich is sending the SSS update */ u32bits cl_mon_ownership_view_id;u32bits cl_multicast_nodes; u08bits cl_tx_type; u08bits cl_src_nodeid;u08bits reserved; u08bits cl_cload_th_flag; u32bits cl_cload_cur_load;u32bits cl_tot_mon_lrtm_time; // using zero bytes to accommodate anyname length changes later. char name[0]; // dbs, normal, gslb }sssdata_t;

Now referring to FIG. 8C, an illustrative diagram of a method formonitoring in a cluster system 840. For clarity, only two nodes areillustrated, but one of skill in the art may readily appreciate that thepresent systems and methods may be scaled up to any number of nodeswithin the cluster. In one embodiment, a two-node cluster may includenodes b0 841 and b1 843. Two services S1 and S2 may be executed by eachnode, such as distributed databases or applications. Monitors m1 and m2may be bound to service S1 and m3 and m4 may be bound to S2, based onthe result of a hash applied to information of service S1 and S2. S1 maybe monitored by b0 841, while S2 is monitored by b1 843. In still otherembodiments, within b0, m1 and m2 may be distributed among a pluralityof PEs running on b0 and similarly within b1, m3 and m4 may bedistributed among a plurality of PEs running on b1. Whenever S1's statechanges, b0 841 may inform b1 843 via a service update message 842.Similarly, whenever S2's state changes, b1 843 may inform b0 841 via aservice update message 844.

Now referring to FIG. 8D, a flow diagram of a configuration event in acluster system is illustrated. In some embodiments, a configurationevent may be an event generated from a configuration change (e.g., atopology change to the cluster). In an embodiment, ownership of theservices in the cluster may be redistributed among the nodes in thecluster in response to a configuration event in the cluster. In oneembodiment, the configuration event changes a topology of the cluster.Examples, without limitations, of a configuration change include addingor deleting a service, or naming a service or a service group. Infurther embodiments, when a new service/named service/service groupmember is added, a clustering-specific processing function may performedto distribute monitoring among the active nodes in the cluster, such asan RSS hash of information about each service to distribute monitoringof said services among the nodes. The monitor of a service may generatea service state update for the service in response to the configurationevent in the cluster. The monitor may keep re-transmitting anacknowledgment message to each node in the cluster until each node inthe cluster acknowledges receipt of the service state update.

In some embodiments, to distribute the monitoring, the followingoperations may be performed by the distribute event handler. At step852, the distribute event handler may check if the clustering is enabledor not. If the clustering is not enabled then no operations need to beperformed. At step 853, the distribute event handler may identify if thelocal node is part of the Open vSwitch (OVS). If the local node is notpart of OVS, then no operations will be performed at this time. Wheneverthe node joins the cluster at a later point, then the clusteringspecific operations may performed then. At step 854, the distributeevent handler may determine if the service is an internal service. Ifthe service is an internal service than no monitoring distribution isrequired. At step 855, the distribute event handler may check if theservice is owned by the local node or not. This check may be requireddue to asymmetric configuration of all the services that are not ownedby all the nodes in the cluster. If the node does not own the service,then do not perform any operations. At step 856, the distribute eventhandler may calculate the hash key of the service based on the entityID. At step 857, the distribute event handler may obtain the PRL listand find the first intersection of the node that will be the monitoringowner of the service. At step 858, the distribute event handler maydetermine if the owner node ID is the local node ID.

At step 859, if the local node is the monitoring master of the addservice then, in some embodiments, the distribute event handler may seta flag in the server information, representing the current node as themaster node. In further embodiments, the distribute event handler mayenable the monitoring for the service. In still other embodiments, thedistribute event handler may copy the current view ID from the globallist to the master node. At step 861, the distribute event handler maydetermine if the monitoring distribution was called due to addition of anew service. At step 862, the distribute event handler may set theserver information value to zero. Because the service may be a newservice, no node will have previously updated the service state, so itmay be initialized. At step 863, the monitoring distribution API may becalled to redistribute the existing service ownership. To redistributethe existing ownership, the API may send an SSS broadcast update messageto declare the new ownership and to avoid race conditions. At step 860,if the local node is not the monitoring master of the add service, insome embodiments, the server information monitoring flag is reset andthe server information master view is updated. The monitoring may bedisabled when the new owner updates by sending SSS message.

Now referring to FIG. 8E, illustrated is a flow diagram of aconfiguration change in a cluster system, such as deleting an entity. Insome embodiments, whenever an existing service, named service, orservice group member is deleted, no clustering specific processing willbe required. However, in other embodiments, configuration messages mayneed to be broadcast to avoid race conditions or other errors.

In some embodiments, a quorum service provider may send messages to allnodes in the form of events whenever any node joins or leaves the OVS.When a node event handling occurs, a new application type may beregistered in the PE cluster module and corresponding new applicationhandles will be added to the command list. In further embodiments,multiple events can occur simultaneously. In such cases, the PE willqueue the core to core messaging (CCM) events in a new list for laterprocessing by the system by the PE.

In some embodiments, when a node joins the OVS, an event will begenerated by the Quorum Service Provider (QSP) and it will be sent toall the PEs of all the nodes. The add event message may be queued ontothe CCM events list. Each PE may call the event handler for the joinevent, responsive to receiving the event from the QSP.

Still referring to FIG. 8E, in some embodiments, the followingoperations will be performed by the join event handler. At step 872, thejoin event handler may determine if the clustering is enabled or not. Ifthe clustering is not enabled then no more operations may be necessary.At step 873, the join event handler may identify if the local node ispart of the OVS. If the local node is not part of OVS then no moreoperations need to be performed. At step 874, the join event handler maydetermine if the local node is the new node due to which join event hasbeen received. At step 875, the join event handler may determine if thelocal PE is PE0. At step 877, if the local node is not the newly joinednode then, in some embodiments, the PE0 may only go through all theserver information in the global server and send service state update(SSS) of the services to which the local node is monitoring to the newlyadded node. At step 876, in some embodiments, if the local node is notthe newly added node, then the PE may go through all the serverinformation in the global server and call the distribute event handlerto redistribute the monitoring ownership for all the services in thelist.

Now referring to FIG. 8F, illustrated is a flow diagram illustrating awhen a node leaves a cluster. In some embodiments, when any node leavesthe cluster, for example and without limitation because either it hasgone down or the node has been removed from the cluster byconfiguration, an event will be received by all the nodes in thecluster. In further embodiments, the event notification may betransmitted by a PE. In still other embodiments, the leave event may bequeued onto the CCM events list.

In some embodiments, the following operations may be performed by aleave event handler. At step 882, a leave event handler may determine ifclustering is enabled or not. If the clustering is not enabled than nomore operations need to be performed. At step 883, the leave eventhandler may identify if the local node is part of the OVS. If the localnode is not part of the OVS, then no more operations need to beperformed. At step 884, each of the PEs may access the serverinformation in the global server and call the distribute handler todistribute the monitoring for all the services in the list. In someembodiments, a PE NNM message handling interface may provide facility toparse and call message handlers based on the message groups and theirrespective messages types.

Now referring to FIG. 8G, illustrated is a method 890 for redistributionof ownership of services 821 in a cluster system 800. At step 891, insome embodiments of distributed monitoring within a cluster, a pluralityof nodes 801 may each monitor the services 821 they have ownership of AtStep 892, a change in the number of nodes 801 active in the cluster 800may be detected, or the nodes may receive a notification of a change inthe number of active nodes. In some embodiments, the change may bedetected responsive to a node 801 joining the cluster 800. In otherembodiments, the change may be detected responsive to a node 801 leavingthe cluster 800 or becoming unresponsive. If no change in the number ofnodes 801 in a cluster 800 is detected, the nodes 801 may continue tomonitor the services 821 they each own. At step 893, further comprisingsteps 894-897 in some embodiments, if a change in the number of nodes801 has been detected, the ownership of services 821 may beredistributed among the plurality of nodes 801 active in the cluster800. The services 821, in some embodiments, may be redistributed tobalance the load in the cluster 800. In other embodiments, the services821 may be redistributed equally among the plurality of nodes 801 in thecluster 800. In further embodiments, the redistribution of ownership ofservices 821 may be performed according to method 830 as discussedabove.

At step 894 as part of step 893, a master node 801 for each service 821may be determined based upon a hash value associated with the node 801.At step 895, the new owner of the service 821 may send anacknowledgement to the old owner of the service 821. The acknowledgementmay indicate to the old owner that the service has a new owner node 801.At step 896, the old owner may stop monitoring the service uponreceiving notice from the new owner node 801. The old owner node 801 maycontinue to monitor the services 821 it still has ownership of. If thereare additional services and monitoring duties or ownership toredistribute, then steps 894-897 may be repeated in some embodiments. Inmany embodiments, steps 894-897 may performed iteratively for eachservice for which monitoring is to be redistributed, or may perform thesteps in parallel or serial for the services. For example, step 894 maybe performed for each service, then steps 895 and 896 for each service.

Now referring to FIG. 9A, illustrated is a block diagram of an appliance200 used for monitoring of one or more services 911 across a pluralityof nodes 901 in a cluster system 900 using path monitoring 920(illustrated in dashed lines). The appliance 200 may be a multi-core ormulti-node in a cluster system 900. A node 901 may be a connection pointin a cluster system 900 and may be capable of receiving, transmitting orforwarding information over a network. In the embodiment shown, the oneor more nodes 901 may be associated with one or more network services911. In other embodiments, the one or more nodes 901 may monitor anappliance 200, vServer, network service 911, client, or any othernetwork resource, with each node designated as the “owner” of a service911 a-911 c and monitoring said service (solid line). Each owner maycommunicate status of their monitored service to the other nodes vianode-to-node messaging. Each service 911 may also have a path monitoring920 capability.

In some embodiments, a monitor for a service may enable a pathmonitoring option for the service. The path monitoring 920 may allow allnodes in a cluster to determine reachability to the service withoutcommunicating with the master node 901. In one embodiment, when the pathmonitoring option is enabled, non-owner nodes in the cluster may probethe service to determine a service reachability from the respective nodeto the service. As shown, in some embodiments, path monitoring 920 maybe performed by all nodes 901 in the cluster system 900 to each service911, irrespective of whether a node owns the service or not, to verifyreachability of each service by the node. Once each node has determinedthe service reachability, the non-owner nodes may transmit a pathmonitoring state update to the owner node (e.g., monitor) of theservice. The path monitoring state update may include the servicereachability for the respective node to the service. The monitor of theservice may update a status of the service with the service reachabilityinformation for each node in the cluster.

Now referring to FIG. 9B, a diagram of a method for monitoring of one ormore services 911 across a plurality of nodes 901 in a cluster system.At step 922, the method may include identifying, by a PE in a clustersystem, a service in the cluster system. At step 924, the method mayalso include identifying, by the PE, a master node for the service basedupon a hash value associated with the node. At step 926, the method mayfurther include identifying, by the PE, a path monitoring state for aservice. At step 928, the method further includes transmitting, by themaster node, a service state update of the service, to the other nodesin the cluster system.

The feature of probing the service from all the cluster nodes to checkindividual reachablility may be referred to as Path monitoring. Pathmonitoring may be enabled, configured or disabled via add and setcommands for service and service groups, providing granular control on aper-service level. By default, the pathMonitor option may be disabledfor all the service and service groups. When a PE enables the validatepath option for any given service, each node that owns or executes theservice may start probing the service using ICMP (ping probes). In someembodiments, the effective service state may be calculated at the timewhen SSS update may be received from the monitoring owner of theservice. Individual nodes can have different service state based on theservice reachability from the node.

In some embodiments, the method may include the path monitoring statefor a service 911 being disabled initially. In still other embodiments,the method may include enabling, by a PE, the path monitoring state fora service 911. In further embodiments, the method may include probing,by the master node 901, the service 911 using the path monitor 920 ofthe service. In various embodiments, the service state update of theservice may include both the service state and the path monitoringstate.

In one implementation, the method may include disabling, by a masternode 901, the path monitoring status of a service 911. The pathmonitoring status may be disabled using a service command. In stillother embodiments, the method may include transmitting, by the masternode 901, that the path monitoring 920 of a service has been disabled tothe cluster system 900.

Individual nodes may have different service states based on the servicereachability from the node. In some embodiments, a PE might want tobring down the service on each and every node 901 of the cluster 900,even if only one node 901 is not able to reach the service 911. Forexample, if a plurality of nodes are communicating with a database, andone node is unable to reach the database, a PE may choose to restart theservice rather than have a percentage of requests go unfulfilled. Insome embodiments, the pathMonitorindv option may be enabled by defaultand this option will be configurable only if the validatePath option isenabled. In an embodiment, if the pathMonitorindv is disabled then theservice will be advertised down if one or more nodes are not able toreach the service.

In some embodiments, for any given service, each node may send the pathmonitor state update message to the monitoring owner of the service. Thepath monitoring state update message may consist of two parameters: aunique ID of the service and the current path monitor state. Uponreceiving the “enable path monitoring” command the “default-pathmon”monitor may be created if not present. In further embodiments, themonitor may be bound to the service. In still other embodiments, thepath monitor may be enabled on only OVS nodes, though the “enablepathmon” will be fired on all the online CVS nodes, to ensure no passivenodes will monitor service. The path monitoring cache may be checked soas to fetch all the path monitoring updates from the other OVS nodesthat could have been received before “enable pathmon” command or evenbefore “add service” command was fired on the local node. Then, in someembodiments, the local node PM probe may update the master node with thelocal PM state and the bitmap will be updated accordingly.

In some embodiments, upon receiving the “disable path monitoring”command, the path monitor will be unbound from the service. Onnon-master nodes the backed up state may be re-enforced. The backupstate may store the latest monitoring state told to the node by themonitoring owner. In still other embodiments, on the master node, staterecalculation may be triggered and the MOS will send the SSS updateincase a change in state is detected.

In various embodiments, each and every OVS node might use pathmonitoring, and whenever there is a change in the path monitoring mipstate, the node may broadcast the path monitoring update to all theactive nodes on CVS set. In some embodiments, the incoming traffic maybe redirected from a node n0, which has lost its connectivity with thenetwork or services to other nodes which are still able to reach theservices. In further embodiments, to notify other nodes of the loss ofconnectivity, each vserver and service may have a processing setassociated with it, and the processing set to be updated on each andevery node based on path monitoring bitmap to make it aware of whichservices are reachable from which all nodes.

In further embodiments, such as in the case of master node change,online client virtualization service (CVS), which may not be part ofOVS, can become the new master node. When the CVS becomes the new masternode, the, path monitoring bitmap may be updated along with the servicestate to allow it to monitor and update correctly. In still otherembodiments, when a new node joins to the online CVS set, the node maybe synced with the following information before it may be allowed tobecome part of OVS: each of the MOS nodes may send an SSS update to thenewly joined node and each node may send the path monitoring updates foreach and every service for which path monitor is active.

In some embodiments, when a change in the state of the path monitoringoccurs, the local node may send the path monitoring update via a C2Cmessage to the monitoring master to update, if the monitoring mastercore does not own or is bound to the service. In further embodiments,the node will broadcast the PM update message to all the nodes in theonline CVS. One non-limiting example of a PM update message will be asshown below:

typedef struct nsmc_mon_pm_update_(—) { u32bits pm_bitmap_delta; u32bitspm_bitmap_available_delta; u08bits pm_src_node_id; u08bits pm_res[3];u32bits pm_flags; u32bits sip_uniq_id; }nsmc_mon_pm_update; typedefstruct { nsmc_mon_msg_generic_hdr mon_msg_hdr; u32bits num_updates;nsmc_mon_pm_update updates[0]; } nsmc_mon_pm_update_msg;

In various embodiments, the same structure nsmc_mon_pm_update_msg may besent as payload of node to node path monitoring update message. As thepath monitoring update is broadcast to all the online CVS nodes, theupdate can land on any core on the destination node. Accordingly, thesame core to core messaging service may be used to transmit the remotepath monitoring update to the monitoring master.

In some embodiments, upon receiving the path monitoring update, themaster node may update its local bitmap with the information received inthe path monitoring update, irrespective of whether it is in OVS or notor it is the master node or not. In still other embodiments, if therecipient is not part of OVS, then the node may no longer receive pathmonitoring update messages. In further embodiments, where the recipientnode is part of OVS, then the processing may be based on whether thenode is the master node of the service or not. If the node is the masternode of the service, then in some embodiments, the node will recalculatethe service state based on the updated bitmap and send an SSS updatewith any change in service state. Otherwise, if the node is not themaster node of the service, then it will just digest the path monitoringupdate without doing any processing.

In some embodiments, where the “individual path monitoring decision”option is ENABLED, then all the non-master nodes may override their ownstate if the PM mip state is DOWN. Further, non master nodes may alsotake backup of the service state to reinstate the original state back incase of “disabling of path monitor”. In various embodiments, the backedup state may be refreshed by the SSS update from the master node, incase there is any update while the service state is DOWN on the localnode due to individual path monitoring decision.

The PM updates can be broadcast even if the individual path monitoringdecision option is enabled as possessing set of the services is requiredto be updated. In some embodiments, when the “individual path monitoringdecision” option is disabled, which it may be by default, the masternode may consider the path monitoring bitmap for computation of theservice state and send the service state as down if even a single nodein the current OVS is not able to reach the service. Rest processing maybe the same as in cases where the “individual path monitoring decision”option is disabled.

Now referring to FIG. 9C, illustrated is one illustrative example of amethod for monitoring services in a cluster using path monitors. In FIG.9C, the two-node cluster system has nodes b0 942, and b1 944. Twoservices S1 and S2 are executed on each node, as well as monitors m1 andm2 which are bound to S1 and m3 and m4 which are bound to S2. Pathmonitors P1 932 and P2 934 may be executed for services S1 and S2,respectively. In some embodiments, the path monitor is not bonded to theactual sip. A separate sip may be created for any given service whenevervalidatePath option is enabled.

In one embodiment, a hash of identifiers of service S1 may yield b0 942and a hash of identifiers of S2 may yield b1 944. Accordingly, theactive monitor bindings on each node may include:

on b0 942: m1-S1, m2-S1 are marked active. P1-S1 and P2-S2 are alsoactive; and

on b1 944: m3-S2, m4-S2 are marked active. P1-S1 and P2-S2 are alsoactive.

In further embodiments, whenever a service state changes, each node mayupdate all other nodes about the service state change. The path monitorsmay be enabled on each and every node of the cluster for all theservices. Responsive to status determined by the path monitors, eachnode may send reachability states for the service (e.g. up orreacheable, or down or unreachable) to the monitoring owner of theservice.

In one implementation, for DBS services, there may be two bindings, forexample primary server information and secondary server information. Theownership of the two bindings may be given to the same node as theownership is service based. In further embodiments, whenever there is anIP address change, the owner node may send update to the other nodes inthe cluster as part of SSS (service state) update. The recipient nodemay update the IP address and the service state accordingly. In someimplementations, script based monitoring may be done by the master nodeand states may be transmitted to all the other nodes.

Now referring to FIG. 9D, illustrated is a diagram of a method 950 forhandling monitoring of dynamic response time monitors (DRTM). To handledynamic response time monitors, in some embodiments, the ownership ofall the services to which DRTM monitor has been bounded may be moved tothe same node 901, irrespective of vserver binding, so that no node tonode messages need to be sent. This may be done because response timesmay change every probe and accordingly, sending updated response timesmay be very expensive. In various embodiments, the owner node 901 willknow the response time of all the services to which a DRTM monitor isbound, and therefore can calculate the dynamic timeout intervalsindependently. Accordingly, during redistribution of monitoring dutiesat step 893 of method 890 illustrated in FIG. 8G, if DRTM monitors arebound to services, method 950 may be executed.

Specifically, at step 952, a determination may be made as to whether aservice 911 is bound to a dynamic response time monitor (DRTM). If so,at step 954, a first node 901 may be selected as owner node 901.Although referred to as a “first” node, the first node 901 may be anynode in the cluster system 900, and this term is used simply todifferentiate the DRTM monitoring node from other nodes. In fact, theDRTM monitoring node may, in many instances, be selected via a hashvalue as discussed above for the first iteration of step 954. If aservice 911 is not bound to a DRTM, at step 956, an owner node 901 for aservice may be identified based upon a hash value associated with thenode 901 as discussed above. In some embodiments, Step 956 may be thesame method as method 920. If there are other services for whichmonitoring needs to be distributed, then steps 952-958 may be repeatedfor each additional service. When the same service or another servicebound to a DRTM comes up during an iteration of steps 952-958, the same“first” node may be selected at step 954, such that the chosen node isutilized for monitoring all services bound to a DRTM. In manyembodiments, steps 954 and 956 may each include steps 895-896 of method890 of FIG. 8G discussed above.

In some embodiments, to handle least response time method (LRTM), themonitoring will be distributed by the standard monitoring distributiondiscussed above and the MOS may send response time, LRTM messages orupdates to all the other nodes. In various embodiments, the totalresponse time may be used by all the nodes to perform load balancing.The LRTM message, may be sent only after current monitor hassuccessfully sent at least one SSS update to all the nodes in someembodiments. In still other embodiments, the LRTM update may only besent if at least one LRTM enabled monitor is attached with the serviceand the service is bound to at least one vserver whose load balancingmethod is set to LRTM. In further embodiments, the LRTM informationmessage may be sent only if the total response time has diverted by atleast 5% from the last sent value. The LRTM info may also be synced withthe SSS update before the node joins OVS.

In some embodiments, to handle custom loading distributions, themonitoring may be distributed by standard monitoring distribution andthe MOS may send the following information to all the other nodes:threshold reached flag, load learnt from the load monitors and roundrobin (Rr) contributions. In various embodiments, the above threeparameters may be used by all the nodes to perform load balancing incase load balancing method is set to least load. The custom load messagemay only be sent after current monitor has successfully sent at leastone SSS update to all the nodes. In some embodiments, the custom loadupdate may send only an if at least one custom load enabled monitor isattached with the service. The custom load info message may only besent, in some embodiments, if either load has diverted by at least 5%from the last sent value or the threshold flag has changed. In someembodiments, the custom load info may be synced with the SSS updatebefore the node joins OVS.

In some embodiments, because traffic may be evenly distributed amongnodes, a simple monitor may be sufficient for the requirement ofmonitoring a cluster system. For example and without limitation inlineHTTP/S monitor and traffic monitor TCP.

I. Systems and Methods for Application Specific Load-Balancing

The systems and methods of the present solution illustrated in FIGS.10A-11B are directed towards load balancing among servers based onapplication and application availability. Currently in some deploymentsof application load-balancing among backend servers, all back-endservers have the same set of applications and are homogeneous in termsof application availability. The present solution allows for servers tobe heterogeneous in terms of application availability and load-balancingcan be performed among them. Each of the servers may have differentapplications actively present on them and/or some applications may bepresent on some services but not others in a plurality of servers. Aload balancing server intermediary to a plurality of clients and aplurality of services executing on a plurality of servers can handleclient requests for applications based on application availability andforward the request to service based on application availability.

FIG. 10A is a block diagram of a system for application specific loadbalancing for servers, such as web servers. In more detail, FIG. 10Adepicts an appliance 200 intermediary to a plurality of clients 102 a-n,and a plurality of services 1010 a-n executing on a plurality of servers106 a-n. The appliance may perform load balancing for the plurality ofservers 106 a-n based on applications available on each of the services1010 a-n executing on the plurality of servers 106 a-n. Each of theservices 1010 a-n may include one or more applications 1015 a-n activelypresent and/or available.

In a brief overview, the appliance 200 includes a virtual server,referred to as a vServer 275, a plurality of monitoring agents 1020 a-c,and a table 1030. The appliance 200 and its various components may besimilar to the appliance 200 described above, for example with respectto FIGS. 1A-9D. In some embodiments, the appliance 200 provides loadbalancing among servers 106 in responding to requests from clients 102.The requests may identify a specific application by an identifier. Theappliance 200 may load balance requests from clients 102 based upon theavailability of applications 1015 active on the services 1010 andcorresponding to the identifier.

An application 1015 may be any type of program, library, script orexecutables instructions, group of programs, or software designed toperform a predetermined or specific function or provide a certain set ofservices or functionality. In some embodiments, the application maycomprise any type and form of database and/or database related services.For example and without limitation, an application may include at leastone of a database program, web browser, word processor, developmenttools, image editing programs, or communication programs.

The vServer 275 may receive, intercept or otherwise processescommunications between a client 102 and a server 106 in accordance withthe configuration and operations of the appliance 200. The monitor 1020may be referred to as a monitoring agent. Each of the plurality ofmonitoring agents 1020 a-n may comprise any program, script, daemon, orother computing routine that reports a performance or operationalcharacteristic of a service 1010 a-n to the appliance 200. The monitor1020 may communicate with a service 1010 to determine a number ofapplications 1015 present on the service 1010. In some embodiments, themonitor 1020 may use a request/reply messaging mechanism or protocolwith the server. In one embodiment, responsive to probing a service1010, a monitor 1020 may transmit a monitor response to the appliance200. The monitor response may indicate the number of applicationspresent on the service 1010. In some embodiments, a single monitor 1020may monitor a plurality of servers 106. In other embodiments, aplurality of monitors 1020 may monitor a single server 106. In stillother embodiments, a plurality of monitors 1020 may each monitor aplurality of servers 106, wherein each of the plurality of servers 106is monitored by a plurality of monitors 1020. The monitor may be similarto the monitoring agents described above with respect to FIGS. 7A-9D.

In the embodiment shown, the one or more monitors 1020 are associatedwith one or more services 1010 executing on one or more servers 106. Inother embodiments, the one or more monitors 1020 may monitor anappliance 200, vServer, network service 270, client, or any othernetwork resource. The monitor 1020 may be similar to the monitoringagents described above with respect to FIGS. 7A-9D.

The table 1030 may comprise a data structure or object stored ormaintained in memory. The table 1030 may comprise a table, datastructure or object stored or maintained in storage or a database. Thetable 1030 may include an application list 1035, referred to as anapp_list, and a temporary list 1040, referred to as a temp_list. Theapplication list 1035 may include a list of applications activelypresent on a plurality of services 1010 a-n. The temporary list 1040 maybe a temporary list of applications dynamically creating during anupdate of the table 1030. The temporary list 1040 may be used to compareagainst the application list 1035 to determine if the number ofapplications actively present on the plurality of services 1010 a-n haschanged. The table 1030 will be described in greater detail below withrespect to FIG. 10B.

FIG. 10B is a block diagram of an embodiment of a table on an applianceused for load-balancing among servers. For clarity, only one table 1030is illustrated, but one of skill in the art may readily appreciate thatthe present systems and methods may be scaled to include any number oftables 1030. A table 1030 (e.g., GLOBAL_APP_HASH_TABLE) may bemaintained for storing a list of application populated from monitorresponses received from various monitors established for each service1010. In some embodiments, the GLOBAL_APP_HASH_TABLE may be referred toas the first table. In an embodiment, the mapping for the table 1030 maybe done according to a hash value of the application name (e.g.,app_name). The various fields of information of the table 1030 mayinclude an application name, an identifier, a service, and a monitor.Each entry of the table 1030 may correspond to an application 1015present on one or more of the services 1010 a-n. In an embodiment, eachentry of the table 1030 may include information related to a particularapplication 1015, the identifier assigned to the application, a service1010 that the application is actively present on and a monitor 1020established for the service 1010. In other embodiments, the table 1030may be organized in any way to store information related to at least oneof an application, a service, a web server, or a monitoring agent.

In an embodiment, an entry in the table 1030 may be established when oneor more monitors 1020 are bound to a service 1010. Once a monitor 1020has been bound to a service 1010, the monitor 1020 may probe and/orquery the respective service 1010 to determine a number of applicationsactively present on the service 1010. The appliance 200 can receivemonitor responses from each of the monitors 1020 indicating the numberof active applications present on the respective service 1010. Theappliance 200 can populate the table 1030 using the results of themonitor queries and probes.

Each application identified by the plurality of monitors 1020 can beassigned an identifier and added to the table 1030. In an embodiment,the mapping for the table 1030 can be done by the identifier assigned toeach application 1015. In some embodiments, the identifier may be a hashvalue of the application name. In other embodiments, the identifier canbe any form and/or combination of letters, numerals, or characters. Eachentry of the table may be based on the application name (app_name). Thetable can be created for any number of applications on any number ofservices. In one embodiment, the table can be created to storeinformation for up to 2048 number of applications on each service.

In some embodiments, a second table may be maintained (e.g.,GLOBAL_DEVNUM_HASH_TABLE). In the second table, each entry may be basedon the application name (app_name) and mapping for the second table maybe done using a hash value of an identifier (dev_number). The secondtable may include an identifier list including all of the identifiersassigned to each application and identifiers not assigned to anyapplication yet. In some embodiments, the appliance 200 may query thesecond table to determine the corresponding identifier to anapplication. In other embodiments, the appliance 200 may query thesecond table to select an unused identifier and assign the identifier toan application. In some embodiments, the first table and the secondtable may include similar information, however the second table may beorganized by the identifier and the first table may be organized by theapplication name. In other embodiments, the second table may be similarto the first table.

In an embodiment the table 1030 may be designed as described below:

app_name { dev_number;  /* 4 bytes*/ hash; /* 4 byte*/ namelength; /* 2byte*/ ref_count;  /* 1 byte*/ appname[256];  /* 256 byte*/ app_name *next_app; }

The next app may be for linklist type hash implementation ofGLOBAL_APP_HASH_TABLE. The application list 1035 may include a list ofall applications available on each of the services. In some embodiments,the application list 1035 may be organized based on identifiers assignedto each application 1015. For example, in an embodiment, each entry inthe application list may be identified by a dev_number assigned to eachapplication 1015 and corresponding to that application 1015. On eachservice, an application list character pointer (app_list char pointer)can be added to indicate whether or not a particular application 1015 ispresent on a service 1010. When the service 1010 is bounded with amonitor 1020 a number of bytes can be allocated to the service 1010 inthe application list 1035. In one embodiment, when the service 1010 isbounded with a monitor, 256 bytes are allocated to the service in theapplication list 1035. Each bit may represent an application 1015. Theapplication character pointer can point to a particular bit in theapplication list 1035 to indicate whether or not the correspondingapplication 1015 is present on the service 1010. For example, in oneembodiment, when a bit is set to 1 in the application list 1035, thiswill indicate that the application is present on the correspondingservice 1010. In another example, in one embodiment, when a bit is setto zero in the application list 1035, this indicates the correspondingapplication 1015 is not present on the corresponding service 1010.

In an embodiment, the table 1030 may include a temporary list(temp_list) 1040 to store information during an update of the table1030. The appliance 200 may copy and/or transfer the information in theapplication list 1035 to the temporary list 1040 prior to a tableupdate. Once the application list 1035 has been populated with theresults of the monitor responses, the appliance 200 may compare theapplication list 1035 to the temporary list 1040 to identify anychanges. The appliance 200 may analyze the comparison to determine ifthe status of an applications has changed or if a new applications hasbeen detected. In an embodiment, the temporary list 1040 may be the samesize as the application list 1035.

Referring now to FIG. 11A, a flow diagram depicting an embodiment ofsteps of a method 1100 for application specific load balancing forservers is shown and described. In brief overview, the method includesreceiving a request from a client for an application (Step 1105) andidentifying an identifier for the application from a table comprising alist of applications and a corresponding identifier assigned to eachapplication (Step 1110). The method further includes determining thatone or more services of the plurality of services provides theapplication (Step 1115). The method further includes selecting a servicefrom the one or more services to forward the request (Step 1120) andforwarding the request to the selected service (Step 1125).

In further detail, at step 1105, the device may receive a request from aclient for an application. In an embodiment, the device is an appliance.In some embodiments, the device may be an device intermediary to aplurality of clients and a plurality of services executing on aplurality of servers. The request may include the application name or anidentifier associated with the application. In some embodiments, when aclient sends a request with an application name (e.g., app_name), theappliance may verify one or more conditions to select a service. Theconditions may include at least one of: is the service enabled (e.g.,active, usable), does the service contain the application, is themonitor for the service is enabled, or is the monitor binded to theservice.

The appliance may establish one or more monitors to monitor each serviceto identify applications available on each service. Monitors can probeand/or query the respective service to identify active applicationspresent on the service. The appliance can receive monitor responses fromthe probes indicating the number of applications present on eachservice. The appliance may maintain, responsive to monitoring by the oneor more monitors, a list of applications in a table available for eachservice. The appliance may establish a global has table including thelist of applications present on all of the services. For eachapplication identified an application entry is established in the table.The application entry may include a identifier (e.g., dev_number) whichcan be used to search for the application in the table.

At step 1110, the appliance can identify an identifier for theapplication from a table comprising a list of applications and acorresponding identifier assigned to each application. The appliance mayquery, search or look up in the table for the respective identifierbased on the application indicated in the client request. The appliancemay use the application name, a hash of the application name, or anykind of information associated with the application to search the tablefor the respective identifier. In some embodiments, the appliance mayquery, search or look up in a second table for the identifiercorresponding to the requested application. In an embodiment, theappliance may query, search or look up in any number of tables toidentify the identifier corresponding to the requested application. Inan embodiment, to search for a particular application on a service, theappliance can retrieve, obtain or identify the identifier (e.g.,dev_number) from the table (e.g., GLOBAL_APP_HASH_TABLE).

In an embodiment, the identifier may be pre-established by a program oradministrator. In other embodiments, the identifier may be created bythe appliance, for example, during load-balancing functions. In someembodiments, to find an available identifier, a global bitmap ismaintained. Each bit in the global bit map may represent an identifier(e.g., dev_number). To find the next available identifier, for example,when adding a node to the table, the device can scan the bitmap for anunused identifier.

At step 1115, the method further includes the appliance determining thatone or more services of the plurality of services provides theapplication. Responsive to retrieving the identifier, the appliance canparse the application entry using the identifier to determine whichservice or services has the requested application. Responsive todetermining which service or services has the requested application, theappliance can check the corresponding bit in the application list forthe respective service. For example, the following logic may be used todetermine if a particular application is present on a service:

If((app_list[d/8]&(1<<(d%8)))!=0)

In an embodiment, if this logic is true, the application is present onthe service. In some embodiments, the appliance can query a second tablecomprising a list of identifiers available for each service. Theappliance may query the second table to determine which applications areactively present on each of the services based on the identifier. In anembodiment, the appliance can determine that the one or more servicesare identified in the second table with the identifier corresponding tothe application.

At step 1120, the appliance can select a service from the one or moreservices to forward the request. In an embodiment, the appliance mayselect the service based on the query of the first table and/or thequery of the second table. The appliance may select the service based onmultiple conditions, including at least one of: is the service enabled(e.g., active, usable, available), is the application present on theservice, is the monitor for the service is enabled, or is the monitorbinded to the service. In an embodiment, the appliance may select theservice that is determined to be available. In some embodiments, theappliance may determine that a monitor is enabled for the service andthe service has the application. The appliance may determine if one or acombination of the conditions are met by analyzing the results of thequery of the table. In some embodiments, the appliance may store theresults of the queries of the table to compare to a subsequent query ofthe table. In an embodiment, the appliance may select the service basedon a comparison of different queries of the table.

In an embodiment, if a service is disabled, the appliance may not selectthis service. In some embodiments, the appliance may determine theservice is enabled and update the table corresponding to the respectiveservice to indicate the service is enabled. In an embodiment, an extrafield can be added to the service to indicate whether the monitor isenabled or disabled. The appliance may query this field to determine ifa monitor is enabled for a service. In some embodiments, if a monitor isdisabled, the previous entries can be stored and recorded in case themonitor is enabled again. In some embodiments, to bind a monitor to aservice, a pointer can be added to a service. For example, in anembodiment, the pointer may point to a bit map rather than using acomplete bit map. When a monitor is bound to a service, any number ofnumber of bytes can be allocated. In one embodiment, 256 bytes may beallocated when a monitor is bound to a service. In some embodiments, thebytes may be allocated from memory.

In an embodiment, to unbind a monitor from a service, the appliance cande-allocate the bytes allocated to the service during monitoring. In anembodiment, to select a service, the appliance may check if the pointerfor the respective service is NOT NULL. NOT NULL may mean the monitor isbound. If the monitor is bound to the service, the appliance may selectthe service. If the pointer is not bound to the service, the appliancemay not select the service. In some embodiments, when a monitor isunbound from the service, the reference count, referred to sometimes asref_count may be decreased. In other embodiments, when a monitor isunbound from the service, the application entry may be removed for allapplications containing the given service.

In an embodiment, if a service is removed, the ref_count can bedecreased. In other embodiments, if a service is removed, theapplication entry form the global hash table can be removed for all theapplications present on that service. In some embodiments, if aservice-group is removed, the ref_count can be adjusted for eachapplication on every service for that service-group in the global apphash table.

At step 1125, the appliance may forward the request to the selectedservice. In an embodiment, the appliance may forward the request to theservice that meets all four the conditions. In other embodiments, theappliance may forward the request to the service that meets acombination of the conditions. The appliance may forward the request forthe application to the service executing on a server to handle theclients request.

Referring now to FIG. 11B, a flow diagram depicting an embodiment ofsteps of a method 1150 for monitoring servers to load-balance among theservers is shown and described. In brief overview, the method includesestablishing one or more monitors to monitor each service to determineapplications available on each service (Step 1155) and determining anumber of applications available on each service (Step 1160). The methodfurther includes assigning an identifier to each application availablevia the plurality of services (Step 1165) and maintaining a tablecomprising identification of each service of the plurality of servicesand a list of identifiers corresponding to each application availablevia each service (Step 1170).

At step 1155, an appliance intermediary to a plurality of servicesexecuting on a plurality of servers may establish one or more monitorsto monitor each service to determine applications available on eachservice. One or a plurality of monitors can be added to each service tomonitor and/or query the respective service. In an embodiment, theappliance may establish one or a plurality of monitors executing on theappliance to probe each of the services. In some embodiments, themonitors may be detected to a single service. In other embodiments, themonitors may probe multiple services. The monitor can determine thenumber of active applications present on each service.

At step 1160, the appliance may determine, responsive to monitoring, anumber of applications available on each service. The appliance mayreceive the monitor responses from probes by each of the monitorsestablished for each of the services. The monitor responses may indicatethe number of applications on the respective service. In someembodiments, the monitor responses may include an application name andthe application status (e.g., active, available). The appliance mayanalyze the monitor responses to determine number of applicationsactively present on each service. In some embodiments, the appliance maystore the monitor responses from each monitor. The appliance may comparesubsequent monitor responses from each of the monitors to identify anystatus changes in the number of applications available on each service.

At step 1165, the appliance may assign an identifier to each applicationavailable via the plurality of services. In some embodiments, theappliance may maintain an identifier list (e.g., global bitmap) in whicheach entry in the identifier list represents an identifier (dev_number).In one embodiment, the appliance may maintain a global bitmap in whicheach bit represents an identifier. When a node is added to the table,the appliance may scan the identifier list and find the next availableidentifier. In an embodiment, the size of the identifier list may be upto 256 bytes. The identifier may be a numeral or an alphabeticcharacter, or a combination of them.

At step 1170, the appliance, responsive to monitoring, maintains a tablecomprising identification of each service of the plurality of servicesand a list of identifiers corresponding to each application availablevia each service. In an embodiment, the table may be a global hash tablethat is maintained for storing a list of application for services. Theappliance may establish a table to store information associated withvarious applications executing on a plurality of services executing on aplurality of servers. The appliance may load balance requests forapplication based on the different applications available on each of theservices. The appliance may create an application entry for eachapplication identified by the monitor responses. The application entriesin the table may be organized by a hash of the application name andmapping may be done to each of the entries by the hash value of theapplication name. In other embodiments, the mapping of the table may bedone by a hash value of the identifier assigned to the application. Theappliance may create the application entries responsive to receiving themonitor responses as a new application is identified. Each applicationentry may include an identifier assigned to the respective application,a hash value, a namelength value, a ref_count value, and the applicationname.

In an embodiment, the appliance may establish or maintain a second tablecomprising a list of applications and corresponding identifiers assignedto each application. In many embodiments, the second table is a portionof the first table and/or is part of the same table incorporating thefirst table. In some embodiments, the second table may include a list ofidentifiers corresponding to each applications. The mapping for thesecond table may be done by a hash value of the identifier. In otherembodiments, the mapping of the second table may be done by a hash valueof the application name. In an embodiment, the second table may includesimilar information as the first table, however the second table mayorganize the information differently. For example, in one embodiment,the second table may organize the information by the identifier assignedto the various applications.

For each application entry in the table, an identifier (e.g.,dev_number) will be assigned to the respective application. Theidentifier can be used to look whether that application is present on aservice. In response to receiving a request for an application, theappliance can search the respective application entry in the table andretrieve the identifier. Using the identifier, the appliance candetermine if the particular application is present on a service.

In an embodiment, the appliance may copy the application list in thetable to a temporary list to update the table, such as response to oupon the appliance updating the list of applications in the table,Responsive to copying the application list to the temporary list, theappliance may set the corresponding bits in the application list tozero. To update and/or add to the table, the appliance can receivemonitor responses from each of the monitors at each probe. In anembodiment, each application identified by the monitors can be added tothe first table by using hash value of the respective application name.In some embodiments, each application can be added to the second tableby using hash value of the respective identifier assigned to theapplication. The appliance can add or update the tables responsive todetermining if any of the applications identified in the monitorresponses are new applications. In an embodiment, to determine if theapplication is already listed in the list of applications, the appliancecan scan the table using the application name.

If one of the applications identified is a new application, theappliance can search, query or look up an identifier list for a newidentifier and assign the new identifier to the new application. In anembodiment, the new identifier may be the next available identifier in alist of identifiers. In other embodiments, an order of identifiers maybe predetermined by a program or by an administrator. Responsive toassigning the identifier to the new application, the bit in theapplication entry in the table corresponding to that identifier can beset to the appropriate value. For example, in one embodiment, the bitfor an identifier may be set to 1 once the identifier has been assignedto an application.

If the appliance determines the application is already listed in theapplication list, the appliance can retrieve the respective identifierfor the application. In some embodiments, to determine if theapplication is already listed in the table, the appliance can parse thetable using the application name and identify the correspondingidentifier. In an embodiment, once the identifier has been retrieved,the appliance can set the appropriate bit value (e.g., 0, 1) for theapplication entry corresponding to the respective service theapplication was identified on.

For example, in an embodiment, to set a bit for dev_number d, thefollowing code may be used:

app_list[d/8]|(1<<(d%8))

The bits may be set for each application present on that service. Onceall of the bits have been set responsive to monitoring, the appliancecan compare the temporary list to the application list in the table. Forexample, in an embodiment, the appliance may XOR the temporary list andthe application list. The XOR, also referred to as an exclusivedisjunction or exclusive or, is a logical operation that outputs true(e.g., 1) whenever both inputs differ (e.g., one is “1” true and one is“0” false). In some embodiments, if a bit is set to 0 in the applicationlist and set to 1 in the temporary list, the comparison outputs true forthat bit because both inputs are different. The output of true mayindicate a change in a status of an application or a new application notpreviously active on the service. As result of the comparison, onlythose bits that remain at 1 may indicate a change in the application.For example, the bits remaining at 1 as a result of the comparison mayindicate at least one of a new application or an application which hasbeen removed. An application which has been removed may include anapplication that is no longer active on a service.

In an embodiment, the bits which are 1 in XOR list and also in app_listmay be the corresponding applications which have been added to theservice. To update the table with the applications which have beenadded, the appliance identifies the bytes that are 1 in both the XORlist and the ap_list. The appliance then determines and/or calculates acorresponding identifier (dev_number) for each of the new applicationsand assigns the identifier to the respective application. Responsive toassigning the identifier to the application, the appliance can find theappropriate application entry in the table for the new application andincrease the ref_count by 1 for that application.

In other embodiments, the bits which are 1 in XOR list and in temp_listmay be the corresponding application which have been removed from theservice. To update the table with the applications which have beenremoved or no longer active, the appliance can find the correspondingidentifier (dev_number) for that bit. In an embodiment, using theidentifier, the appliance can find the application name in the table anddecrease a ref_count to 1 for that application. In other embodiments,using the identifier, the appliance can find the application name in thetable and remove corresponding entry one or from all tables on theappliance corresponding to that application. These steps can be carriedout for each service that the appliance receives monitor responses backfrom and/or each service identified in any of the tables executing onthe appliance.

In some embodiments, every time the appliance starts updating a list,the appliance may copy the app_list to temp_list and set all bits ofapp_list to zero first for every service in a service-group. Forexample, the following code may be used:

app_list[i]=01000100 (latest mapped bits)

temp_list[i]=00100100 (previously mapped bits)

(app_list[i])XOR(temp_list[i])=01100000

Added application=01000000 (application corresponding to this bit isadded)

Identifier (dev_number) corresponding to this application:

devnumber=6+i*8

In an embodiment, the application corresponding to this identifier canbe found using the second table (e.g., GLOBAL_DEVNUM_HASH_TABLE).Responsive to identifying the application name, the appliance can addthis entry to the first table (e.g., GLOBAL_APP_HASH_TABLE). In someembodiments, if the entry already exists on the table, the appliance canincrease the ref_count by 1 for that entry. In an embodiment, theappliance may identify an application to be removed based on thecomparison:

-   -   Removed application=00100000 (application corresponding to this        bit is removed)    -   Identifier (dev_number) corresponding to this application:    -   devnumber=5+i*8

In an embodiment, the application corresponding to this identifier canbe found using the second table (GLOBAL_DEVNUM_HASH_TABLE). Responsiveto identifying the application name, the appliance can remove this entryfrom the table (GLOBAL_APP_HASH_TABLE). In some embodiments, responsiveto identifying the application name, the appliance can decrease theref_count by 1 for that entry. In an embodiment, the appliance canupdate the table responsive to the comparison.

In the case of n-core architecture, every time a core receives an updateof applications, the update can be sent to all other cores to notifythem of the changes. In an embodiment, for every new update, thereceiving core can broadcast the message, which contains a list of allof the applications, to all of the other cores in the n-corearchitecture.

The structure of the message broadcast to all of the cores may include avalue for an entity_id, view_id, multicast nodes, version, Pkt(i). Where“Entity_id” entry represents a unique id for each service. The unique idwill be same across all the nodes and all the cores. In an embodiment,the “Entity_id” entry in the broadcast message may be 8 bytes. The“View_id” entry represents an id used in a cluster to check validity ofmessage. For example, in some embodiments, the “View_id” can be used todetermine if the correct monitor owner of the service broadcast themessage and not from an old monitor owner of the service. In anembodiment, the “View_id” entry in the broadcast message may be 8 bytes.The “Multicast nodes” entry represents the other nodes in the cluster towhom the broadcast message is sent to and/or multicast. In anembodiment, the “Multicast nodes” entry in the broadcast message may be4 bytes. The “Version” entry represents the message version. In anembodiment, the value of 1 may be used cur type of messages. In otherembodiments, the “Version” entry can be if some changes are made to themessage. The “Version” entry in the broadcast message may be 1 bit. The“Pkt(i)” entry in the broadcast message can be 2 bytes. In anembodiment, the “Pkt(i)” entry or packet entry may include len andappname. “len” may refer to the length of the application name.“appname” may refer to the name of the application, for example bytesused equal to len.

In an embodiment, each message may comprise the number of packets equalto number of applications on that service. For example, the message mayinclude Pkt1 to PktN entries for N number of applications on therespective service. When the message is broadcast, each of the cores canreceive the message and parse it to identify changes in the list ofapplications. The receiving core can update a list of applications on ahash table or tables local to the receiving core and update the bitmapsapp_list to the corresponding service.

In an embodiment, in the case of n-cluster, every time a core isreceiving an update, the core can broadcast the updated list message,the same message format that is used for n-core, to all the nodes in thecluster. Each cluster node can receive the updated list message on acore. Responsive to receiving the message, the core can again broadcastthis updated list message to all the cores in that node. In someembodiments, whenever a new node is joins a cluster, for exampleN-cluster, the complete list of applications can be sent to the newlyadded node. In an embodiment, to send the list of applications to thenode, a multicast API in N2N can be used. In an embodiment, the new nodeor nodes can be in operational view state (OVS) at the time the messageis being unicast or multicast. The message may contain the complete listof applications.

During transmission of a message in an n-core, if the message fails, themessage may be re-transmitted to the other cores. In an embodiment, aflag can be added to a service to indicate when a message transmissionfails. For example, in one embodiment, a flag “insi_cur_w_flags” isadded to a service, corresponding to the bit (NSI_W_APPSLB_C2C_FAIL). Inthe case of a message failure, the bit can be set to 1 to indicate themessage transmission has failed. A timer can called after an interval oftime and for each service, the appliance can check whether this flag is1 (ON) or not. In an embodiment, the interval of time can bepredetermined and be set to any period of time. In other embodiments,the interval of time can be dynamically changed during load-balancingoperations. If the flag is set to 1, this may indicate a message failureand the message can be re-transmitted to all of the cores. If there-transmission of the message is successful, the flag can be set to 0(OFF). If the re-transmission of the message fails, at the next intervalof time, the message can be re-transmitted again to all of the cores.This process can continue until all of the cores have received themessage.

During transmission of a message in a n-cluster, if the messagetransmission fails, the message may be re-transmitted to all of theother nodes and to all cores in those nodes. A 4 byte field may be addedto each service, “sql_nodemask.” In an embodiment, this field may have anodemask of nodes for which the transmission of the message failed. Whenthe transmission of a message fails to one or more nodes a callbackhandler may get a call or indication of the message failure. Inside thecallback handler, the field sql_nodemask can be set to nodemask of nodesfor which the message transmission failed. A timer can get a call afteran interval of time to indicate when to check each service forsuccessful transmission of the message or message failure. In anembodiment, for each service, the appliance can check if the fieldsql_nodemask value is set to 1 (ON) or not zero. If the value is set to1, the message can be re-transmitted to all of the other nodes and coresin those nodes. If the re-transmission of the message is successful, thefield value can be set to 0 (OFF). If the re-transmission of the messagefails, at the next interval of time, the message can be re-transmittedagain to all of the nodes and cores in those nodes. This process cancontinue until all of the nodes and cores in those nodes have receivedthe message.

In some embodiments, in both n-core/n-cluster re-transmission, themessage being transmitted can be formed at the time of transmissionusing the bitmap present in the respective service for which there-transmission is performed for.

In a cluster, the monitoring owner node of any given service can startsending an application (APP) update message immediately after receivingthe “bind 1 b monitor service command.” In an embodiment, this may leadto a race conditions between the APP update message which would begenerated by the owner and reception of the “bind 1 b monitor service”command on other nodes. For example, in one embodiment, the APP updatecan reach a node which has not received the “bind 1 b monitor service”command at that point of time. In some embodiments, if the bind 1 bmonitor command has not reached the node, then the receive side willreturn a message failure indication to the owner node and the owner nodecan re-transmit and/or unicast the APP message to that node.

In some embodiments, if APP updates are transmitted by two master nodesduring a view change, each of the outgoing clustering messages can betagged with a current view id of the sender node. For example, in oneembodiment, the node N0 is the monitoring owner for the service S0 andhas just sent a APP update (APP1 APP2) for S0 and then the node N0 goesdown. The QSP can detect that the node NO has gone down and updates theview. In this example, node N1 can be selected as the new monitoringowner of S0 and it may start probing the service. The APP on S0 can beupdated as follows (APP1 APP2 APP3). N1 may send an APP update (APP1APP2 APP3) to the rest of the nodes. In some embodiments, the APP updatefrom N1 may reach the node Nn before the APP update from the node N0. Tohandle this scenario, each of the outgoing clustering messages (e.g.,APP updates) with the current view id of the sender node.

In an embodiment, the view id can be part of the NNM header in the NNMmessage. The server_info can be stamped with the view id of the lastmessage which has updated the service state. In some embodiments, when anew SIP update is received, the view id of the new incoming message canbe compared with the stamped view id in the server_info. The APP listmay be updated when the view id in the message is greater than or equalto stamped view id of the server_info. When the APP list is updated withthe APP list from the received APP update message, the server_info(server_info(si_cl_applist_mon_owner_view_id)) can be updated with viewid of the received message.

In some embodiments, during a transmission of message (e.g., APP update)a race condition may exist between an APP update and a view change. Forexample, a cluster may include three nodes N0, N1 and N2 and, N0 is thecurrent view leader. An administrator may try to “bind 1 b monitorservice” to the cluster. The nodes N0 and N1 may have received the “bind1 b monitor service.” command and may conclude that N0 is the MOS, butN2 has not received the command till now. In this example, the node N0may start probing immediately and may send the APP update message to allof the nodes. Since the node N2 has not received the “bind 1 b monitorservice” command till now, the applist will be updated only on N0 and N1and not on N2. The node NO can keep trying to re-transmit the APP updateto N2, as it is waiting for N2 to receive the “bind 1 b monitor service”command. If the node N0 goes down before N2 has received the “bind 1 bmonitor service” command and N1 becomes the MOS, N2 will NOT receive theAPP update even after receiving the “bind 1 b monitor service S1”command, as N1 will not send the APP update until there is a change inthe APP list of S1 again.

To handle this, in the case of a change in the ownership of monitoringfor any given service, the new owner can broadcast the latest APP listknown to it, so that new owner node can update all the nodes which mighthave missed or left behind by the last MOS. In an embodiment, theclustering messages (e.g., APP updates) can be sent in the following twocases, first a change in the APP list on a service and second, a changeof ownership of the monitoring for any given service.

It should be understood that the systems described above may providemultiple ones of any or each of those components and these componentsmay be provided on either a standalone machine or, in some embodiments,on multiple machines in a distributed system. The systems and methodsdescribed above may be implemented as a method, apparatus or article ofmanufacture using programming and/or engineering techniques to producesoftware, firmware, hardware, or any combination thereof. In addition,the systems and methods described above may be provided as one or morecomputer-readable programs embodied on or in one or more articles ofmanufacture. The term “article of manufacture” as used herein isintended to encompass code or logic accessible from and embedded in oneor more computer-readable devices, firmware, programmable logic, memorydevices (e.g., EEPROMs, ROMs, PROMs, RAMs, SRAMs, etc.), hardware (e.g.,integrated circuit chip, Field Programmable Gate Array (FPGA),Application Specific Integrated Circuit (ASIC), etc.), electronicdevices, a computer readable non-volatile storage unit (e.g., CD-ROM,floppy disk, hard disk drive, etc.). The article of manufacture may beaccessible from a file server providing access to the computer-readableprograms via a network transmission line, wireless transmission media,signals propagating through space, radio waves, infrared signals, etc.The article of manufacture may be a flash memory card or a magnetictape. The article of manufacture includes hardware logic as well assoftware or programmable code embedded in a computer readable mediumthat is executed by a processor. In general, the computer-readableprograms may be implemented in any programming language, such as LISP,PERL, C, C++, C#, PROLOG, or in any byte code language such as JAVA. Thesoftware programs may be stored on or in one or more articles ofmanufacture as object code.

While various embodiments of the methods and systems have beendescribed, these embodiments are exemplary and in no way limit the scopeof the described methods or systems. Those having skill in the relevantart can effect changes to form and details of the described methods andsystems without departing from the broadest scope of the describedmethods and systems. Thus, the scope of the methods and systemsdescribed herein should not be limited by any of the exemplaryembodiments and should be defined in accordance with the accompanyingclaims and their equivalents.

What is claimed:
 1. A method comprising: (a) receiving, by a deviceintermediary to a plurality of clients and a plurality of servicesexecuting on a plurality of servers, a request from a client for anapplication; (b) identifying, by the device, an identifier for theapplication from a table comprising a list of applications and acorresponding identifier assigned to each application; (c) determining,by the device using the identifier, that one or more services of theplurality of services provides the application; (d) selecting, by thedevice, a service from the one or more services to forward the request;and (e) forwarding, by the device, the request to the selected service.2. The method of claim 1, further comprising establishing, by thedevice, one or more monitors to monitor each service to identifyapplications available on each service.
 3. The method of claim 2,further comprising maintaining, by the device responsive to monitoringby the one or more monitors, the list of applications in the tableavailable for each service.
 4. The method of claim 1, wherein (c)further comprises querying, by the device using the identifier, a secondtable comprising a list of identifiers available for each service. 5.The method of claim 4, further comprising determining, by the device,that the one or more services are identified in the second table withthe identifier corresponding to the application.
 6. The method of claim1, wherein (d) further comprises selecting, by the device, the servicethat is determined to be available.
 7. The method of claim 6, furthercomprising determining, by the device, that a monitor is enabled for theservice and the service has the application.
 8. A method comprising: (a)establishing, by a device intermediary to a plurality of clients and aplurality of services executing on a plurality of servers, one or moremonitors to monitor each service to determine applications available oneach service; (b) determining, by the device responsive to monitoring, anumber of applications available on each service; (c) assigning, by thedevice, an identifier to each application available via the plurality ofservices; and (d) maintaining, by the device responsive to monitoring, atable comprising identification of each service of the plurality ofservices and a list of identifiers corresponding to each applicationavailable via each service.
 9. The method of claim 8, wherein (b)further comprises receiving, by the device, responses from probes of theone or more responses, the responses indicating applications availableon the respective service.
 10. The method of claim 8, wherein (d)further comprises establishing, by the device, a second table comprisinga list of applications and corresponding identifiers assigned to eachapplication in the list of applications.
 11. The method of claim 10,wherein (d) further comprises: comparing, by the device responsive tomonitoring, the list of identifiers available for each service in thetable; and updating, by the device, the table responsive to thecomparison.
 12. The method of claim 8, further comprising receiving, bythe device, a request from a client for an application.
 13. The methodof claim 12, further comprising identifying, by the device, theidentifier for the application and determining using the identifier viathe table, that one or more services of the plurality of servicesprovides the application.
 14. The method of claim 13, further comprisingselecting, by the device, a service from the one or more services toforward the request and forwarding, by the device, the request to theselected service.
 15. A system comprising: a device intermediary to aplurality of client and a plurality of services executing on a pluralityof servers, the device configured to: receive a request from a clientfor an application; identify an identifier for the application from atable comprising a list of applications and a corresponding identifierassigned to each application; determine, using the identifier, that oneor more services of the plurality of services provides the application;select a service from the one or more services to forward the request;and forward the request to the selected service.
 16. The system of claim15, wherein the device is further configured to establish one or moremonitors to monitor each service to identify applications available oneach service.
 17. The method of claim 16, wherein the device is furtherconfigured to maintain, responsive to monitoring by the one or moremonitors, the list of applications in the table available for eachservice.
 18. The method of claim 15, wherein the device is furtherconfigured to query using the identifier, a second table comprising alist of identifiers available for each service.
 19. The method of claim18, wherein the device is further configured to determine that the oneor more services are identified in the second table with the identifiercorresponding to the application.
 20. The method of claim 15, whereinthe device is further configured to select the service that isdetermined to be available.